The Ford Mustang Boss 302, Boss 429, and Mach 1 (1969–1973) were Ford's racing and performance Mustangs, built for Trans Am homologation and drag racing. The 1969–1970 Boss 429 (375hp, semi-hemi) is the rarest and most valuable Mustang, at $200,000–$350,000 (#2) — only 859 built. The 1969–1970 Boss 302 (290hp, actual ~350hp) is the Trans Am homologation special, at $65,000–$95,000 (#2). The 1969–1970 Mach 1 with the 428 Cobra Jet (335hp, actual ~400hp) is the best value performance Mustang, at $45,000–$70,000 (#2). The 1971–1973 Mach 1 with the 429 CJ (370hp) is the entry point at $35,000–$50,000 (#2). The Boss 429 is the holy grail of Mustangs — rarer than the Shelby GT500 and more valuable than all but the GT350 R-model.
The Racing Mustangs: Boss, Mach 1, and Trans Am
In 1969, Ford launched two homologation specials and one performance package that would define the Mustang's racing legacy. The Boss 302 was built to homologate the 302ci engine for SCCA Trans Am racing, where Ford competed against Chevrolet's Camaro Z/28. The Boss 429 was built to homologate the 429ci semi-hemi engine for NASCAR — Ford wanted to run the engine in the Torino but NASCAR required it in a minimum number of production vehicles, so it was shoehorned into the Mustang. The Mach 1 was the performance luxury package — not a homologation special but a street performance Mustang with the 351W, 390, or 428 CJ. The 1971–1973 Mustangs grew larger and heavier, and the Boss 302/429 were discontinued after 1970. The Mach 1 continued through 1978 but with declining power.
| Variant | Years | Engine | HP | Purpose | Production | Collectibility |
|---|---|---|---|---|---|---|
| Boss 302 | 1969–1970 | 302ci V8 (semi-hemi) | 290 (actual ~350) | SCCA Trans Am homologation | ~7,000 | Very High — Trans Am racing heritage; most collectible small-block Mustang |
| Boss 429 | 1969–1970 | 429ci V8 (semi-hemi) | 375 | NASCAR homologation | 859 | Ultra High — rarest and most valuable Mustang; holy grail; semi-hemi |
| Mach 1 428 CJ | 1969–1970 | 428ci Cobra Jet | 335 (actual ~400) | Street performance | ~12,000 | Very High — best value performance Mustang; 428 CJ power; iconic styling |
| Mach 1 351W | 1969–1970 | 351ci Windsor V8 | 250–290 | Street performance (base Mach 1) | ~20,000 | High — good value; less powerful than 428 CJ; most common Mach 1 |
| Mach 1 429 CJ | 1971–1973 | 429ci Cobra Jet | 370 (1971) | Street performance (top engine) | ~3,000 | Very High — rare; 1971 only for 429 CJ; most collectible 1971–1973 Mach 1 |
| Mach 1 351C | 1971–1973 | 351ci Cleveland V8 | 240–285 | Street performance (most common) | ~50,000 | Medium — most common 1971–1973 Mach 1; good value; less collectible |
| Mach 1 351C CJ | 1971–1973 | 351C Cobra Jet | 266–285 | Street performance (upgraded) | ~8,000 | High — 351C CJ is best 1971–1973 engine; good value; collectible |
| Mustang Grande | 1971–1973 | 250ci I6, 302ci V8, 351C V8 | 145–285 | Luxury Mustang | ~50,000 | Low — luxury trim; no performance appeal; not collectible |
The Boss 429 (859 built) is the rarest and most valuable Mustang — a NASCAR homologation special with a semi-hemi 429. The Boss 302 (~7,000 built) is the Trans Am racing homologation special — the most collectible small-block Mustang. The Mach 1 428 CJ (~12,000 built) is the best value performance Mustang — 428 CJ power at half the Boss 302 price. The 1971–1973 Mach 1 351C is the most common and affordable — good for a driver-quality car.
Production Numbers
| Year | Boss 302 | Boss 429 | Mach 1 (all) | Mustang Total | Notes |
|---|---|---|---|---|---|
| 1969 | ~1,600 | ~340 | ~24,000 | ~300,000 | Boss 302/429 launch; Mach 1 introduced; 428 CJ available; peak year |
| 1970 | ~5,400 | ~519 | ~28,000 | ~190,000 | Boss 302 restyled (shark mouth); Boss 429 continues; last Boss year |
| 1971 | N/A (Boss dropped) | N/A (Boss dropped) | ~36,000 | ~150,000 | All-new larger body; 429 CJ available; Mach 1 only performance Mustang |
| 1972 | N/A | N/A | ~27,000 | ~125,000 | 351C top engine; 429 gone; emissions hurting; power declining |
| 1973 | N/A | N/A | ~25,000 | ~135,000 | 351C top engine; safety bumpers; last year of classic Mustang; declining |
Production data from Ford Motor Company. The Boss 429 (859 total: ~340 in 1969, ~519 in 1970) is the rarest Mustang variant. The Boss 302 (~7,000 total) is the Trans Am homologation special. The Mach 1 was the most popular performance Mustang — ~140,000 across 5 years. The 1969–1970 Mustangs (smaller, lighter) are more collectible than the 1971–1973 models (larger, heavier). Total Boss/Mach 1 production: ~147,000.
Engine Specifications
| Engine | Displacement | Years | HP | Torque | Notes |
|---|---|---|---|---|---|
| 250ci I6 | 250ci | 1969–1973 | 155–170 | 234–257 | Base I6; very slow; no collector appeal |
| 302ci V8 | 302ci | 1969–1973 | 210–250 | 300–335 | Base V8; Windsor small-block; no performance appeal in Mustang |
| 351W V8 | 351ci | 1969–1970 | 250–290 | 335–385 | Windsor small-block; Mach 1 base engine; good value; less common than 351C |
| 351C V8 | 351ci | 1971–1973 | 240–285 | 319–380 | Cleveland small-block; 351C Cobra Jet (285hp); best 1971–1973 engine |
| 351C CJ | 351ci | 1971–1973 | 266–285 | 319–380 | 351C Cobra Jet; 4-barrel; best 1971–1973 Mach 1 engine; good value |
| 390ci V8 | 390ci | 1969 | 265–320 | 385–427 | Mid-range 1969; FE big-block; replaced by 351W in Mach 1 |
| 428 Cobra Jet | 428ci | 1969–1970 | 335 | 440 | Top Mach 1 engine; actual ~400hp; Ram Air; most collectible Mach 1 engine |
| 428 SCJ | 428ci | 1969–1970 | 335 | 440 | Super Cobra Jet; Drag Pack; 4.30 gears; rare; more valuable than CJ |
| Boss 302 | 302ci | 1969–1970 | 290 | 290 | Semi-hemi heads; solid lifters; Trans Am racing; actual ~350hp; most collectible small-block |
| Boss 429 | 429ci | 1969–1970 | 375 | 450 | Semi-hemi heads; NASCAR homologation; rarest Mustang engine; 859 built |
| 429 Cobra Jet | 429ci | 1971 | 370 | 450 | 4-barrel; 1971 Mach 1 top engine; rare; less valuable than Boss 429 |
| 429 SCJ | 429ci | 1971 | 375 | 450 | Super Cobra Jet; Drag Pack; 4.30 gears; rarest 1971 Mustang engine |
The Boss 429 (375hp, semi-hemi) is the king of Mustang engines — only 859 built, the rarest and most valuable. The Boss 302 (290hp, actual ~350hp) is the Trans Am racing engine — semi-hemi heads, solid lifters. The 428 CJ (335hp, actual ~400hp) is the best value big-block — most collectible Mach 1 engine. The 428 SCJ (Drag Pack) is the rarest Mach 1 engine. The 351C CJ (285hp) is the best 1971–1973 engine. The 429 CJ (370hp, 1971 only) is the most collectible 1971 Mustang engine.
Boss 302, Boss 429, and Mach 1: Three Legends
The Boss 302 was built to homologate the 302ci engine for SCCA Trans Am racing, where Ford competed against the Camaro Z/28. The engine had semi-hemispherical heads (designed by cylinder head guru George Bolth), solid lifters, and a 4-barrel carb. Rated at 290hp, it actually produced ~350hp. The Boss 302 won the Trans Am championship in 1970 with Parnelli Jones driving. Total production: ~7,000 across 2 years. The 1969 has a more refined front end; the 1970 has the aggressive "shark mouth" grille. The Boss 302 is the most collectible small-block Mustang.
The Boss 429 was built to homologate the 429ci semi-hemi engine for NASCAR. Ford wanted to run the engine in the Torino, but NASCAR required 500 production units, so the engine was shoehorned into the Mustang with a modified shock tower and unique front suspension. Rated at 375hp, the engine was actually detuned for the street — the racing version produced 600+hp. Total production: 859 (340 in 1969, 519 in 1970). The Boss 429 is the rarest and most valuable Mustang — $200,000–$350,000 (#2). All Boss 429s were built by Kar Kraft, Ford's racing partner.
The Mach 1 was the Mustang's performance luxury package: aggressive styling (hood scoop, rear deck spoiler, sport mirrors, chrome pop-open gas cap), sport interior (high-back buckets, woodgrain trim, Rim Blow steering wheel), and a choice of engines from the 351W to the 428 CJ. The 1969–1970 Mach 1 with the 428 CJ (335hp, actual ~400hp) is the most collectible — 440 lb-ft of torque in a 3,300-lb car. The Mach 1 was not a homologation special — it was a street performance package. Total 1969–1973 Mach 1 production: ~140,000. The Mach 1 name returned on the Fox Body (2003–2004) and the S550 (2021+).
Market Values by Condition (2026)
| Variant | #1 Concours | #2 Excellent | #3 Good | #4 Fair | 5-Year Trend |
|---|---|---|---|---|---|
| 1969–1970 Boss 429 | $500,000 | $300,000 | $180,000 | $80,000 | +55% |
| 1969–1970 Boss 302 (shark mouth) | $130,000 | $90,000 | $50,000 | $22,000 | +35% |
| 1969 Boss 302 (first year) | $120,000 | $82,000 | $45,000 | $19,000 | +32% |
| 1969–1970 Mach 1 428 SCJ Drag Pk | $100,000 | $70,000 | $38,000 | $16,000 | +30% |
| 1969–1970 Mach 1 428 Cobra Jet | $90,000 | $62,000 | $34,000 | $14,000 | +28% |
| 1971 Mach 1 429 SCJ Drag Pk | $95,000 | $65,000 | $36,000 | $15,000 | +28% |
| 1971 Mach 1 429 Cobra Jet | $75,000 | $52,000 | $28,000 | $12,000 | +25% |
| 1969–1970 Mach 1 351W (290hp) | $60,000 | $42,000 | $22,000 | $9,500 | +20% |
| 1971–1973 Mach 1 351C CJ (285hp) | $55,000 | $38,000 | $20,000 | $8,500 | +18% |
| 1971–1973 Mach 1 351C (240–266hp) | $45,000 | $30,000 | $16,000 | $6,500 | +15% |
| 1969–1970 Mustang 390 (320hp) | $40,000 | $27,000 | $14,000 | $5,500 | +12% |
| 1971–1973 Mustang 302 (210–250hp) | $30,000 | $20,000 | $10,000 | $4,000 | +8% |
| 1971–1973 Mustang Grande 351C | $30,000 | $20,000 | $10,000 | $4,000 | +8% |
| 1969–1973 Mustang 250ci I6 | $22,000 | $15,000 | $7,500 | $2,500 | +5% |
Values from Mecum, Barrett-Jackson, Bring a Trailer, and Hemmings sold data (2024–2026). The Boss 429 (859 built) is the most valuable Mustang — $300,000 (#2), appreciating 15–20% annually. The Boss 302 is the most collectible small-block Mustang — $90,000 (#2) for the 1970 shark mouth. The Mach 1 428 CJ is the best value performance Mustang — $62,000 (#2) for 428 CJ power. The 1971–1973 Mach 1 351C is the best entry point — $30,000 (#2). The Boss 429 is worth more than a Shelby GT500 and is second only to the GT350 R-model ($1M+) in Mustang collectibility.
Value Trend Chart (2020–2026)
Ford Mustang Boss/Mach 1 Average Values (#2 Condition)
| 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | 2026 | |
|---|---|---|---|---|---|---|---|
| Boss 429 (#2) | 200000 | 240000 | 270000 | 285000 | 295000 | 300000 | 300000 |
| Boss 302 1970 (#2) | 60000 | 72000 | 80000 | 85000 | 88000 | 90000 | 90000 |
| Mach 1 428 CJ (#2) | 42000 | 50000 | 56000 | 59000 | 61000 | 62000 | 62000 |
Boss 302 vs Camaro Z/28 vs Trans Am 400: The Pony Car Wars
| Factor | Mustang Boss 302 | Camaro Z/28 (LT1) | Firebird Trans Am 400 |
|---|---|---|---|
| Platform | Ford F-body (108" WB) | GM F-body (108" WB) | GM F-body (108" WB) |
| Engine | 302ci semi-hemi (290hp, ~350hp) | 350ci LT1 (350hp) | 400ci Ram Air (335hp) |
| Torque | 290 lb-ft | 380 lb-ft | 430 lb-ft |
| 0-60 mph | ~6.5 sec | ~5.8 sec | ~6.2 sec |
| Quarter Mile | 14.6 @ 98 mph | 14.2 @ 100 mph | 14.3 @ 99 mph |
| Weight | ~3,300 lbs | ~3,400 lbs | ~3,600 lbs |
| Trans Am Racing | Won 1970 (Parnelli Jones) | Won 1968–1969 (Mark Donohue) | Not raced in Trans Am |
| Production | ~7,000 (2 years) | ~20,000 (2 years) | ~3,900 (1 year) |
| Value (#2) | $82,000–$90,000 | $45,000–$65,000 | $100,000–$140,000 |
The Boss 302 won the 1970 Trans Am championship — the only year Ford beat Chevrolet in the pony car wars. The Camaro Z/28 won in 1968–1969 with Mark Donohue. The Boss 302 has less torque than the Z/28 (290 vs 380 lb-ft) but is lighter and more agile. The Firebird Trans Am is the most valuable of the three due to the Trans Am name and 455 SD. The Boss 302 is the most collectible small-block Mustang and the only one with a Trans Am championship.
Key Option Codes
Ford Mustang Boss/Mach 1 Option Codes
| Code | Name / Description |
|---|---|
Boss 302 | Boss 302 Package 302ci semi-hemi V8 (290hp, ~350hp); solid lifters; Trans Am homologation; 1969–1970; ~7,000 built |
Boss 429 | Boss 429 Package 429ci semi-hemi V8 (375hp); NASCAR homologation; Kar Kraft built; 1969–1970; 859 built; rarest Mustang |
Mach 1 | Mach 1 Package Performance luxury: hood scoop, spoiler, sport interior, 351W/390/428 CJ; 1969–1973; ~140,000 built |
R-code | 428 Cobra Jet Ram Air 335hp (actual ~400hp); functional ram air; 1969–1970 Mach 1; most collectible Mach 1 engine |
R-code SCJ | 428 Super Cobra Jet 335hp; Drag Pack; 4.30 gears, oil cooler; 1969–1970; rarest Mach 1 engine |
J-code | 429 Cobra Jet 370hp, 450 lb-ft; 4-barrel; 1971 Mach 1 top engine; rare; less valuable than Boss 429 |
Q-code | 429 Super Cobra Jet 375hp; Drag Pack; 4.30 gears; 1971 only; rarest 1971 Mustang engine |
G-code | Boss 429 Engine Semi-hemi 429; 375hp; NASCAR; 859 total; built by Kar Kraft; rarest Mustang engine |
F-code | Boss 302 Engine Semi-hemi 302; 290hp (~350hp); solid lifters; Trans Am; 1969–1970; most collectible small-block |
C6 | C6 3-Speed Automatic Heavy-duty automatic; available on Mach 1; not available on Boss 302; preferred for drag racing |
Top Loader | 4-Speed Manual Ford Top Loader close-ratio; standard on Boss 302/429; preferred by collectors; most desirable |
Traction-Lok | Limited-Slip Differential Ford limited-slip; 3.00–4.30 ratios; essential for CJ/SCJ; standard on Boss 302 |
Drag Pack | Drag Pack Option 4.30 rear gears, engine oil cooler, forged pistons; on SCJ; 1969–1971; rare; adds 20–30% value |
SportsRoof | Fastback Body Style Sloped rear roofline; standard on Boss 302/429; most desirable body style; all Mach 1 were SportsRoof |
Buying Guide
- Best investment: 1969–1970 Boss 429
- Semi-hemi 429; 375hp; 859 built; $300,000 (#2)
- Rarest and most valuable Mustang; NASCAR homologation; Kar Kraft built
- Verify Boss 429-specific parts: semi-hemi heads, KK build number, modified shock towers, build sheet
- Best Trans Am heritage: 1970 Boss 302 (shark mouth)
- 290hp (~350hp) semi-hemi 302; Trans Am champion; $90,000 (#2)
- 1970 shark mouth grille is more aggressive and more collectible than 1969
- Verify Boss 302-specific parts: F-code engine, solid lifters, semi-hemi heads, build sheet
- Best value big-block: 1969–1970 Mach 1 428 Cobra Jet
- 335hp (actual ~400hp); 440 lb-ft; $62,000 (#2)
- 80% of Boss 429 torque at 20% of the price; best value performance Mustang
- Verify 428 CJ engine code, Ram Air, dual exhaust, Mach 1 package
- Best drag racer: 1969–1970 Mach 1 428 SCJ Drag Pack
- 335hp; 4.30 gears, oil cooler; $70,000 (#2)
- Rarest Mach 1 engine; Drag Pack adds 20–30% value; built for drag racing
- Verify SCJ-specific parts: 4.30 gears, oil cooler, Drag Pack code on build sheet
- Best 1971: Mach 1 429 Cobra Jet
- 370hp 429 CJ; 1971 only; $52,000 (#2)
- Rare; last year for 429 in Mustang; most collectible 1971 Mustang
- Verify 429 CJ engine code, 4-barrel carb, dual exhaust
- Best value 1971–1973: Mach 1 351C CJ
- 285hp 351C CJ; 4-barrel; $38,000 (#2)
- Best 1971–1973 engine; good value; great driver
- Verify 351C CJ engine code, 4-barrel carb, Mach 1 package
- Best entry point: 1971–1973 Mach 1 351C (base)
- 240–266hp 351C; $30,000 (#2)
- Most affordable Mach 1; good driver-quality car; iconic styling
- Verify Mach 1 package: hood scoop, spoiler, sport interior
- Avoid: 1971–1973 Mustang Grande with 250ci I6
- 155–170hp; luxury trim; no performance appeal; not collectible
- Only buy as a cheap project or parts car
- Better to buy a 1971 Mach 1 351C than a Grande I6
Frequently Asked Questions
- What is the difference between Boss 302, Boss 429, and Mach 1?
- The Boss 302 (1969–1970) was built for SCCA Trans Am racing homologation — a 302ci semi-hemi V8 with solid lifters. The Boss 429 (1969–1970) was built for NASCAR homologation — a 429ci semi-hemi V8, only 859 built. The Mach 1 (1969–1973) was a street performance package with a choice of engines (351W, 390, 428 CJ) — not a homologation special. The Boss 302 won the 1970 Trans Am championship. The Boss 429 is the rarest and most valuable Mustang. The Mach 1 is the best value performance Mustang.
- Why is the Boss 429 so expensive?
- Only 859 Boss 429s were built (340 in 1969, 519 in 1970) — the rarest Mustang variant. The engine was a semi-hemispherical 429 designed for NASCAR, shoehorned into the Mustang with modified shock towers and unique front suspension. Each car was hand-assembled by Kar Kraft, Ford's racing partner. The engine was rated at 375hp but the racing version produced 600+hp. The Boss 429 is worth $300,000 (#2) — more than a Shelby GT500 and second only to the GT350 R-model ($1M+) in Mustang collectibility.
- Did the Boss 302 win the Trans Am championship?
- Yes — the Boss 302 won the 1970 SCCA Trans Am championship with Parnelli Jones driving for the Bud Moore Engineering team. This was the only year Ford won the Trans Am manufacturer's championship in the pony car era. Chevrolet's Camaro Z/28 won in 1968 and 1969 with Mark Donohue driving for Roger Penske. The Boss 302's Trans Am championship is a major part of its collectibility — it's the only Mustang with a Trans Am title.
- Is the Mach 1 a good investment?
- The 1969–1970 Mach 1 with the 428 Cobra Jet ($62,000 #2) is the best value performance Mustang — 428 CJ power (actual ~400hp, 440 lb-ft) at 20% of the Boss 429 price. The 428 SCJ Drag Pack ($70,000 #2) is even rarer and more collectible. The 1971–1973 Mach 1 351C CJ ($38,000 #2) is the best entry point. The Mach 1 is appreciating 15–20% annually — less than the Boss 302/429 but still strong. The Mach 1 is the smart collector's choice — performance, styling, and value in one package.
- What is the difference between a Boss 429 and a 429 Cobra Jet?
- The Boss 429 (1969–1970) had semi-hemispherical heads, designed for NASCAR racing. It was rated at 375hp and built by Kar Kraft. Only 859 were built. The 429 Cobra Jet (1971) was a standard 429 with 4-barrel carb and wedge heads, rated at 370hp. It was available in the Mach 1 and was much more common. The Boss 429 is worth $300,000 (#2); the 429 CJ is worth $52,000 (#2). The Boss 429 is 6x more valuable because of its semi-hemi heads, NASCAR heritage, and extreme rarity.
Get an AI-powered valuation for your Ford Mustang Boss 302, Boss 429, or Mach 1 — free, instant, based on real auction data.
Value My MustangSources & References
- Hagerty Price Guide — Valuation Tools — Independent valuation data by condition grade #1-#4
- Bring a Trailer — Auction Results — Real-world auction sale prices for market comparison
- Related: Fox Body Mustang Generation Hub — In-depth related guide from our editorial library
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- Related: First Gen Camaro 1967 1969 Hub — In-depth related guide from our editorial library
