I moved this thread from Parts for Sale. Carry on with the tech discussion...
I've heard/read that the tubes in a FSJ 20 are much beefier than a CJ 20. I stitch welded the tubes into my CJ 20, but the finally bent. Now its trussed, but I haven't got around to getting the rest of the CJ up and running. I think one piece shafts are a must in a model 20 axle, dunno if the FSJ 20 has factory one pieces shafts or not; 2-piece in the CJ.