i just bought a motor . they say it's a 428. i can't find the stamp on the block by the drivers side motor mount that says 428
rear distributor hole is #L016
block code YH
NUMBERS BY THE BLOCK IS 187828
mine has it ,it is also a YH 68 block
9792968 number at the rear of the block on the pass side
H059 + 8 near the dist hole
I have also had a YH 400 block was a 1974
no number by the motor mount
also had a YH 455 block at one time before 1972
i talked to the guy for a while and had a real good feeling. i talked to pontiacgreg out of denver. he helped me with the numbers and says it's a 428 also!! thanks for your help.