some 340 block vin #'s

Model years varied at Hamtramck a bit, but each model year always started the previous calendar year.

As an example, the 1970 model year began August 1, 1969. So finding 1969 engine casting dates in 1970 model year cars is very common.

The actual engine assembly dates for small blocks will be on the front of the block, right below the driver's side head surface.