I have a '79 F250 Ranger 2wd 400 C6 trans....which I bought from the original family. I have completely removed the block, cleaned, and rebuilt. I can not find a VIN stamped anywhere in the block. I am confident that it is the original 400. A friend with a similar '79 says he had the same problem, and never found a VIN stamp. Does anyone know why this is? Thanks. JC