1969 Ford Mustang Boss 429
Mustang · Engine too wide for stock Mustang engine bay. Kar Kraft move... · The most powerful Mustang of the muscle era — and the hardest to build
Collectible
Production & Overview
Total Production
859
Original MSRP
$4,798
Assembly Plants
Dearborn, MI (then modified at Kar Kraft, Brighton, MI)
Wheelbase
108 inches
Body Styles
SportsRoof Fastback
Curb Weight
3,474 lbs
Available Engines
429 Boss 429ci — V8
NASCAR race engine in street tune. Dry-deck design, cross-bolt main caps, four-bolt mains. Factory underrated — actual output est. 500hp. Modified engine bay required for fitment.
375 hp
Buyer Checklist
⚠ Clone warning: Non-matching engine loses 60-70%+. Always verify with cowl tag, engine stamp, and registry before purchase.
Order Marti Report — Z engine code confirms Boss 429
Verify Kar Kraft build tag — unique to Boss 429
Inspect modified front suspension — Kar Kraft repositioned mounts
Verify engine pad stamp matches VIN
Check modified engine compartment — wider than stock Mustang
4-speed only — no automatic was available
Inspect floor pans and frame rails for rust
Check for correct Magnum 500 wheels
Verify front motor mounts are Kar Kraft relocated design
Road test: 429 Boss has massive torque curve different from 302
Known Problem Areas
Engine removal difficulty — complex modified bay
Kar Kraft modifications affect parts interchange
Floor pan rust
Fake Boss 429 conversions — any big block Mustang can be made to look similar
Missing Kar Kraft tag
Transmission replacement with automatic
What Drives Value
↑ Increases Value
Numbers-matching with Marti Z code and Kar Kraft tag
4-speed correct
Original color with correct engine
Raven Black or Royal Maroon — desirable colors
Low mileage documented
↓ Decreases Value
Missing Kar Kraft tag
Non-matching engine
Automatic transmission
Converted non-Boss
Restoration Overview
Difficulty
High — Kar Kraft modifications complicate restoration
Parts Availability
Fair — some Kar Kraft parts unavailable
Driver Quality Cost
$80,000 – $150,000
Show Quality Cost
$180,000 – $350,000
Key Suppliers
National Parts Depot · Marti Auto Works · Boss 429 specialists
Pop Culture & Legacy
The most extreme factory Mustang of the original muscle car era
Built specifically to homologate the 429 engine for NASCAR racing
Consistently achieves top prices at Barrett-Jackson and Mecum auctions
Other Ford Mustang Boss 429 Years