(1) Were the Protecto-Plates made at the assembly plant or the dealership. (2) When did the engine suffix get stamped on the Protecto-Plate, before or after the engine suffix was stamped on the engine pad.(3) How can I have an engine that was never stamped but has the engine suffix numbers on the Protecto-Plate. I have owned this Corvette since 1967 and it has the original engine. Many thanks for help.