1970 Plymouth Valiant - $1495 (craigslist Arkansas)

It has nothing to do with "the mopar world"
4 doors aren't valuable cars and slant six 3 speed rusty 4 doors are nothing but donors or winter transportation.
Ford, Chevy, Dodge, it doesn't matter. You can have nice driver 4 door cars but they will never have the value of a 2 door. It's reality.
Maybe you'd pay $1500 for that car, I think it's $1000 to high.