What should one look for when looking at used trucks??

[ghost rider]

I was hoping to find out some things to look for when looking to purchase a used truck gas or diesel. What should I stay away from as far as models or years?? I was looking at a 1979 F 350 with a 460 ci for towing my RV. What should I look for as far as things to be aware of?? Gas mileage is not a concern, thanks.

Robs

[silverF250]

In a truck that old oil leaks, rusty frame, cab to frame bushings make sure it is mechaniclly sound and doesn't smoke.