Having a golden opportunity to very closely examine the mod squad 72 challenger convert back in the 90's...The 72 tail panel section was definitely part of the uni body from the beginning- the welds and the seam sealer which were untocuhed - the car was maroon at this pt -were closely inspected & compared to other 70 e bodies we had parked there, etc etc etc. Not an afterthought or factory redo. Rarefish was there and a bunch of others...he might not remember.
So the million dollar question about the 72 B'cuda and 72 Challenger converts- How were they built on the line and were they really built on the Hamtramack assy line or were they built elsewhere and tagged as Hamtrammack cars?
Don't forget that other very odd manufacturing deviations with E bodies have surfaced recently in the form the actual car showing up on the radar. Never say never...