RE: 1970 Challenger R/T build sheet location
If it's not under the rear seat, try the seat backs of the front seats. A few have been found in the dash over the glovebox, or under the carpets, but that's pretty rare. As far as VINs on engine & tranny, they are usually on pads on the passenger side of the components.... engines usually found about halfway back, just above the oil pan, and the trans just above the pan, towards the front on an automatic, and approximately half-way down, towards the front on a manual.