to my knowledge 100% of the 72 -73 E body ragtops were equipped with the Hemi 6 pack
also to my knowledge there are exactly 0 72-73 ragtop E bodies built
Well.......maybe. Someone from here on c-c.com posted this question on Moparts last week and one member there, a credible, knowledgeable long time poster there, replied that he looked at a Challenger convertible for sale in the northeast around 20 years ago, a '72 with '72 sheetmetal. The Vin was JH27G2B100---. He didn't note the full Vin, but said he passed on it because he thought it was overpriced at the time for a 318 car.
With that VIN, he speculated it was a pilot car, and that maybe they made a few before deciding not to do a convertible in '72.
If true, that would be pretty exciting if it surfaces again someday. I wonder if that car is still out there somewhere?