I replaced the floor of a short box with the floor of a long bed

over lap cut at the front of box and over lap cut at rear of the box.

I also added a full set of tubs to the cut 1/2 tubs in the short box.

the gas fill bulge to tub are the same so it all lines up.

I drill all the spot weld out of both beds and then welded them all back up. then welded up the cross cuts.

I had to cut/move one bed mount to line up to the 85 swb frame. the long bed was an 88 and had 1 extra cross brace under there that came out with the mount relocation.

thought about chopping the long bed sides down but that's too much measuring/cutting/welding/body work to get it flat with the body lines straight.

shaving the gas door was not so hard to finish out flat.

but it can be done the long way for sure.

plenty of pics if you want a look.