Block

The heart of it all. The block. Casting numbers on a BOSS 302 blocks: should be C80E-6015-B, C8FE-6015-B for early '69. C9ZE-6015A or B or D0ZE-6015-A for '69. D0ZE-6015-B or C for '70. D1ZE-6015-B for a service block. No, Ford did not make a 1971 BOSS 302 Mustang. Yes, it was planned then canceled. The D1ZE tooling was already cut so it was used for service parts. Not only was the D1ZE-6015-B utilized as a service replacement block, but additionally the D0ZE-C and the D0ZE-B were as well for the '70 Boss, depending on when the replacement took place. The D0ZE-B and the D0ZE-C were also utilized as originally delivered in new '70 BOSS 302s, along with the D0ZE-A blocks. Additionally, the C8FE-B Tunnel Port blocks were also utilized as service replacement blocks in 1969, as the C9ZE blocks were prone to cracking. The C8OE blocks were original equipment on the very, very early '69 BOSS. Yes, some late '69 BOSS' received the D0ZE-A blocks, but no 1970 BOSS' received any C9ZE blocks as some have stated.
Model Year	From the Factory	Service
very early 1969	C8OE-6015-B
1969	C8FE-6015-B C9ZE-6015-A C9ZE-6015-B	C8FE-6015-B
late 1969	D0ZE-6015-A	D0ZE-6015-A
1970	D0ZE-6015-A D0ZE-6015-B D0ZE-6015-C	D0ZE-6015-B D0ZE-6015-C
thereafter		D0ZE-6015-C D1ZE-6015-B
Note the BOSS 302 block features in this photo. Four-bolt main bearing caps, screw-in freeze plugs. Also note the location of the casting numbers hidden by the starter when completely assembled.