I worked at a Plymouth dealer during HS in 77 to early 79 and I remember getting long blocks in with a riveted tag on them to ID them as warranty replacements. I do know they had a stamp set and they would stamp the pad with the VIN number. I also saw them stamp the month and year on the top pad to denote the install date. Was this required..I dont know I just know the tech we had did it. The engines I remember working with were all police Furys so maybe it was something the city wanted done. I never recall getting just a block in they were always long blocks and the claim engine would be shipped back if requested or just sent to the dump if it wasnt. Since these engines were a dime a dozen then no one messed with them.