Originally Posted by h0trod
good luck trying to ID the block, i havnt had much luck with mine.
the most for sure way to find out is by pulling the heads and measuring the bore. however, there is only .005" between a 400 and a 455. there are numbers on the passenger bank on the front face and the rear casting below the head.
mabe youll get lucky!
you can also look under the #1 exhaust port for a cubic inch casting.
if it says 350 or 400, it would be a post 73 block(i know in the 70's they started stamping them, just cant remember what year)
Good call, my '72 400 is casted in the block on the drivers side also. Good luck.