I had a cj7 with quadratrac, nothing but trouble,if its your daily driver its going to be horrible on gas because its always turning the front end,the t-case is weak the chain will loosen and slip at the worse possible time.
I found a cheap donor jeep that i switched the running gear to my jeep. now it has the wide trac axles a little better tire clearence and looks better than those narrow quadratrac axles. still a AMC 20 rear but is centered,the dana 300 t-case is much stronger than the old unit(that didnt even have low range)and has 2-high,4-high,4,low and nuetral, you can even add a twin stick to get 2-low or front wheel drive or something like that(not very familiar with that kit)i also added the t-5 tranny and junked the slush box auto(just my preferance)
if you want to keep the auto you may need an adapter to the D-300. the gearing was different on the new model 20 so i had to swap the front axle as well.was a good time to clean and paint everything while it was out.
I havent seen many upgrades that will fit those off set diff model 20's but that may be just because i was'nt looking
hope this helps some
1982 cj7. Frame off. shell valley kevlar body, stainless hinges, Bestop seats and supertop, KC titanium lights, Homemade swing out tire carrier with spare front wheel bearings/hub, Built 304,DUI,Edelbrock shorty headers with dual stainless 21/2 tubes into incynerator cans 21/4 dumped out the back,Edelbrock 600cfm, performer intake and cam, Borgeson lower column, Centerforce clutch, NV-4500, Dana 300 w/custom built twin stick, Homade 1/4" steel skid plate, 2.5 soft ride w/ 1" shackle lift, 33x12.5 mtr's. Stainless fuel and brake lines, Braided hoses. more...