[bmalone]

As mentioned the three bolts down low and the screw-in freeze plugs are a start. You said the engine was in a car, so obviously you will not be measuring the bore size, but the 427 is.4.23 vs. 4.13 for a 428.

Casting numbers on the block are best, but even that is not foolproof. For instance, side-oilers started production in '65 and and ran through '68. Possible casting numbers are C5AE-X, where C=decade 1960, 5=year of decade, A=car line (Ford in this case), E=engine part, as opposed to say chassis part. X will = some alpha value to indicate change level. You can have C5AE-D, C5AE-H, C6AE-B, C6AE-C, C6AE-D, C7AE-A, C8AE-A, C8AE-B, C8AE-H.

Unfortunately, the 428 uses C6AE-A, C6AE-B, and C6AE-F for the PI motors. All other 428s will have C6ME, C6ME-A, C7ME, C7ME-A, and C8ME for the '66 - '70.

The question is can you read the casting numbers while the engine is in the car?

Bill