GM DID PUT ENGINE CODE # ON RIGHT SIDE OF BLOCK BELOW CYL HEAD EXAMPLE WW IS FOR389-335HP 10.75 COMP RATIO 4 BB CARB MAN TRANS THERE SHOULD BE A SEQUENCE# ABOVE,CODE .IF YOU CAN FIND A BUILD SHEET UNDER FFONT SEAT IN SPRINGS OR BACKSEAT IT WOULD TELL WHICH ENGINE MODEL IT LEFT FACTORY WITH.ALSO BUILD SHEETS MIGHT BE UNDER FLOOR MAT.IF YOUCAN FIND CODE ON ENGINE CAN BRAKE DOWN FOR YOU,LIKE I DID THE WW CODE REFERENCEHOLLANDER INTERCHANGE MANUAL 34TH EDITION