there was someone i knew that had a spool diff. just take it more easy on turns, and said that steering was harder. I didn't go into much detail about them with the person. But his was a Richmond Gear Spool, They are only around 200, i think. 300 tops.. You should get a spool, and not worry about it getting welded, the labor would be a bit i imagine, plus you would want the diff to be heat treated to get the diff, at the greatest tensile strength of the metal.