AMD full quarter panel issue

We were at the big general swap in Conroe, Tx. yesterday. Got into a little conversation with a Chey guy and he told me the reason few of that breed like 56 Chevys....NO one repops any sheet metal for them, just 55 and 57. He said the rear quarter is unique. Who could afford on 56 solid car for a parts car to get the rear qtrs off of!
I figure AMD stops repoping a part because the die is woreout, or not enough demand to do a run and take up warehouse space for how long. Dunno.
All I know is AMD seems to have little love anymore for Mopar in general.
Dunno.