If they are the modern style tube shocks on the rear axle they mount on the inside of the frame rails. There is a bracket assembly that is riveted to the frame with what looks like a long shouldered bolt with threads at the end. The loop end of the shock with its rubber bushings mounts on this. My '54 1 ton panel has this set up. If the shocks are the level arm style ,the shock body bolts thru the frame with either 1/2" or 5/8" bolts. My '48 1 ton pick up had this set up until I made the rear shocks mounts to use the modern style tube shocks. I used '85 full size Ford Bronco shocks for this application. Readily available at any local auto parts store.
