I don't know where they will go. I agree they will never be worth a B or E body. I sure wish I had a couple of my old one's back. You are right the trucks are bringing good money.
There are a lot of variables. I just tried to list some basic groupings. I would say that the pricing depends on whether the car is numbers matching and is a real big block car. That brings a premium. Also in my experiences a 4 speed manual trans usually brings at minimum a $1,000 bump in pricing in a rough car and can go up from there if the car is #'s correct and presents nice. I've seen it add $3,000 to $4,000 to the car.