Chrysler only made about a third of the Cuda, Challenger and other model cars compared to the Camaro and Chevelle, and nobody ever boasted about their Mopar never rusting.
They were built by the worst assembly standards, where the quality was supposed to be inspected in, not engineered into the build.
I spent over a year filling vending machines in Detroit,including Dodge Main, Caddilac, Ford Wayne assembly, and other parts plants, and I can tell you that if you got a Mopar that ran, you were lucky, but it was still going to rust.
There was a reason why Chrysler was #3.
This is the real reason why Mopars are expensive. If you don't build as many cars, and the ones you do build fall apart and rust out so they don't last, the best you can hope for is a barn find.
JMHO