Its interesting and you (of course!) never say never with Ma Mopar, but I have never personally seen a VIN stamped in that location.

I owned a 68 Roadrunner, SO number stamped on bellhouse flange, have an original 68 RR in the shop now for a Body-in-white that had the original engine (not trans) and it has the SO number stamped on bellhouse flange, a friend of mine on Long Island has a 68 Coronet R/T that I went with him to document/validate in wisconsin before he bought it and ..... you guessed it, SO number stamped on the bellhouse flange.

So, lets here from 68 owners with original engines - what do you guys have stamped VIN or SO Number?

NOS Air for everyone (chuckle)