As far as I've seen, the guys that get a 9.25 front diff in there end up saying it'd be easier to start with a 2500hd frame, since they had to re-do every single bracket and you're still left with a 1500 frame. Just 4-link the rear and get it setup to hook in 2wd.

I'd honestly just run 6 lug till you have problems. On a street truck a built 9.5" should hold just fine. I don't think you'd see an issue till you're past 1000 hp/tq

And I'd just do a properly built 4l85e. The allisons are cool for being a 6 spd, but they're sooo damn spendy to build and they still don't handle power well without torque management.

 

i figured the 9.25 would be a bust, so i'm not too worried about it. the rear is already 4-linked stock.

i understand alot of people get the 9.5 to hold but after the swap i will be in the 6500lb range. tahoe weighs a bit more than trucks do. with my power goals, i don't want to put money into one rear to just have it explode and have to build a bigger one. 8.6 is suppose to be pretty strong and i'll agree that it is. but i have broke mine twice. i say that just to make a point that weight plays a big role in the rears. a few guys make big dmax power and run the 9.5" but they are in small trucks that weigh quite a bit less than my tahoe.

the reason for the "torque management" which is just defueling for shifts is because the way it shifts. the ally learn all the time. if you don't defuel during shifts it begins to make itself shift faster to avoid slip. it can get to a point to where it shifts so fast that it will engage one gear before the other is released. which can lock up th back tires for a second and twist stuff inside the trans. this is what i have learned from the guys that build them. also from what i have found so far, there s no "real" time loss at the track for the defuel. it happens faster than a person could shift a manual trans.