[randy500]

I would assemble the entire body on the frame with new body mounts etc to work out all the mount problems and shimming prior to any bodywork. The cab can be difficult to get square to the frame, it’s a critical to get the cab in the right spot or the bed won’t line up looking down the side of the truck. The cab will also probably need to be shimmed so the fenders fit right (front door gap and alignment). Cab height will also effect how the bed fits at the rear of the cab.
Once the cab is set I would try to leave it on for the remainder of the bodywork and paint.
The cab is so heavy it’s difficult to move it tiny amounts which is usually needed.