I may be wrong, but I think the C4 went on small block engines, and the C6 went on big block engines. There was also an FMX transmission, I believe, that might have been a two speed automatic.
I came within a half a second of bidding on the Plymouth. Talked meself out of it, as I have bids on other stuff, and have hit the Buy It Now button too many times, lately.
Several years ago, a show I went to was packing up to go home. The fella that had just won the biggest award for that show couldn't find the model that he built. Everyone thinks it left with one of the spectators.