1969-1971 Ford Mustang Boss guide
Three single-year Boss decks across the 1969-onward Ford intermediate unibody: the 1969-only K-code 302 Cleveland-style head C9OE launch-year, the 1970-onward D0OE Boss 302 + Boss 429 Drag Pak homologation, and the 1971-only Boss 351 Cleveland D1OE 330 hp terminal-year closure.
Ford guide
Ford Mustang Boss · Ford intermediate unibody · $29.95· US-letter PDF
1969-only launch-year Cleveland-style head C9OE-6015-B8 cylinder head at 290 hp on the 1969-only K-code 302 VIN 5th-letter stamping (NOT a 1970-onward D0OE-6015-DA / D0OE-6015-A carryover, NOT a 1971 Boss 351 Cleveland 330 hp fitment, NOT a Boss 429 Semi-hemi Kar-Kraft rail-mounted engine bay mount).
The 1969-only 10.0:1 compression vs the 1970-onward 10.5:1 compression, the 1969 SCCA Trans-Am launch window with Mark Donohue Penske-prepared Boss 302 to the 1969 SCCA Manufacturer's Championship.
Ford guide
Ford Mustang Boss · Ford intermediate unibody · $29.95· US-letter PDF
1970-onward Cleveland head D0OE-6015-DA / D0OE-6015-A casting lineage vs the 1969-only C9OE-6015-B8 stamping.
The 1970-onward 10.5:1 compression bump, the 1970-onward S-code 302 Cleveland engine stamping authentication, the 1970-onward Boss 429 Drag Pak homologation specialty at 375 hp on the 1970-onward D0AE-6015-A Drag-Pak-specific full-hemi cylinder head casting.
Ford guide
Ford Mustang Boss · Ford intermediate unibody · $29.95· US-letter PDF
1971-only Cleveland 351 cylinder head D1OE-6015-AA casting at 330 hp on the 1971-only 11.0:1 compression ratio (the LAST Boss fitment prior to the 1972-onward Boss family retirement closure, NOT a 1970-onward D0OE-6015-DA / D0OE-6015-A Cleveland 302 head, NOT a 1969-only C9OE-6015-B8 Cleveland-style head).
The 1971-onward Boss 302 emissions-era 10.0:1 compression-ratio carryover (DOWN from the 1970-onward 10.5:1 carryover) at 220 hp on the 1971-onward Cleveland 302 D0OE carryover cylinder head.