ive done it the hard way i found a complete 1984 sj-410 robbed the t-case spur gear and did the same to my spare 413 t-case now all i have to do is send them in to trail tuff and have brent do his magic on the 2 of them and send me back a 4.16 crawler gear....my mechanic lives next door to me is doing the work ...now can anyone give me any details on what has to be changed to put this in the t-case ...im kind of leaning twoards the 410 case kuz its only got 50 k miles on it....tom and i have talked about it and we think the low range gear will have to come from the 413 t-case....but i dont know for shure.. tom is one sharp mechanic but he has never done this kind of mod before....is it a p.i.t.a. or is this fairly straight forward swap of parts? rabidray