I'm looking to get an ext. cab truck (89-95). I'm planning on pulling the engine, cab and bed off of the frame (to powdercoat or POR-15 the frame). With the frame bare I would like to do a SAS.
Will having no weight (no engine, drivetrain or body) on the frame mess up my measurements when I do the SAS? Should I weld the SAS components to the frame before I pull the truck apart?

I'm looking at starting this project in January.

 

You should be able to do the whole SAS with the frame bare with the exception of the steering box placement, the steering box frame reinforcement, and the shock towers. The reason I say this is because the steering box WILL be in the way of the body when you put it back on. Depending on how you plan to do the SAS, it may need to be moved forwards. On mine we cut the core support to move it as far forward as possible. Same with the shock towers, mine were tall enough to hit the body, so I had to cut it out some, but I used Ford shock towers. So I would say do all your cutting, grinding, welding, and painting with the frame bare. You can weld on the front hanger, drill and sleeve the shackle holes, hang the springs and mount them up to the axle, so the truck will be able to hold its weight and roll around. Then put the body back on and the engine back in and put on the steering box, frame reinforcement, and shock towers.
Also, I would say don't powdercoat it, you are just going to scratch it up, once the water gets under the PC, you are SOL. I say clean it up real good, use rust converter as necessary, prime it, and POR it.

 

Intrepid, what is a rust converter?

 

I think he means something like this: http://pressroom.eastwood.com/rustconverterrelease.html

Thanks for the info on PC. I'll POR it instead. If I do scratch it, it will be easier to touch up. I'll leave the cab on the frame, have the steering box, and shock hoops installed along with other stuff that might contact the body, then pull the cab and start cleaning.