You would think I could help since I've done it, but I can't do much. The story is on here somewhere, but I have told parts of it other times.
Basically, I custom ordered my '89 F250 new. It went straight to the shop when it came in.
The LWB body was removed and a less than 3 month old SWB body was obtained from the junkyard.
The frame was cut and rewelded with gussets.
The rear gas tank stayed the same, the side tank had to be swapped for a SWB tank.
The driveshaft had to be cut and shortened, because a 1/2 ton used different U-joints than the 3/4 ton. Ford does not make a SWB 3/4 ton.
The exhaust had a factory clamp in spacer that was removed and the two ends fit back together.
The two E-brake cables were removed at the split and a set of SWB cables installed.
The rear brake line had a section with flared fittings on each end that came out and the two ends screwed together.
The fuel lines on that truck were thick black plastic. Rather than installing a SWB line to the rear, the excess was coiled up in a big coil and tied up out of the way.
Other than cutting and welding the frame and driveshaft, everything was pretty much unbolt and bolt together. All the mounting bolt holes on the frame matched. The factory had done the minimum amount of changes between the two versions.
As for the cost, I don't remember for sure. It was over 30 years ago, there was a lot of other stuff done that all got lumped together, and the prices would be a lot different.
Plus, it was a Ford, I have no idea what the philosophy differences are between Ford and GM when it comes to LWB vs SWB frames.
