one thought that MAY work, although i have never used it for a body dolly. i once used 4, short 14" doughnut spares with the matching rear hubs from a couple of minivans to roll around a big truck frame outside in the junk yard. to swivel the front pair, i cut the legs off a pair of big swivel casters and welded them to the legs that were fabbed from 2"x 1/4" angle iron and welded to the minivan hubs. it worked great rolling over rocks and ruts in the yard, plus it was built to get the frame at a comfortable working height. i wished i had pics, but at the time, it didn't seem necessary.