Block ID

ford part #s year break down work like this;first digit is the decade,b=50's,c=60's,d=70's,e=80s etc.Second digit is year,and the rest of the # is were the part is located on the car.An example would be ford part # D1ZE is a 1971 351c cyl. head.You can buy prt # breakdown books or just talk to your local dealer parts guy.Its a great # system vs the brand x guys.

forgot to mention that the date codes are from when the parts are cast,not installed.Its common to see a car with earlier codes on it such as a 74 car with a 73 motor.For what its worth i have a 74 that has a 73 motor(its the original block)and its a 4 bolt main.Im also working on a friends car that is a 72 and it has a 72 motor that is a 2 bolt main.As far as the power of the earlier cars versus later the only difference is compression is higher on the early cars and the camshaft is retarded on the later cars.A quick 30-40 horsepower boost is to put in a good timing chain on a later car.Good as in a true roller or double roller timing set.4 bolt mains are nice but not needed,its not weak in the mains like a small block chevy.

Your OEM block number is stamped just under the rear of the left head, at the back of the block. If original, it matches the engine number on one of the tags on the left inner wheelwell.