Well, what about this 1968 D440hp motor that I got with a '68 GTX that I purchased some years ago. I wasn't too concerned with the whole numbers matching thing but after looking it over very well, it is stamped on the top pad with D440 HP along with 5 23. There is no vin stamping on the pan rail but I did find what looks to be a vin stamp on top of the bell housing right where the trans lines up? Was there something peculiar to the 68 cars? At first I thought that maybe it was replacement but there is no tag. Maybe only Ma Mopar knows for sure!