how strong is the factory diff in a 87 gxl rx7, how much power will they take before they break, I just did a 2j swap and now I am thinking of upgrading the turbo's I want to target about 650 whp, but I wana know how much abuse that factory diff is going to take.

 

what is a good upgrade option if they are not strong and if they are where can I get different gears for it, cause 4.10 is to low for me, I would like 3.55.

 

An NA 7" diff is going to blow up with 650whp. An 8" TII diff will take more abuse, but they're all going to be 4.1. You will have to go with a custom gear set if you want to change it.

 

alot of guys with high HP setups are now going to the ford explorer/lincoln markV custom rearends,v8 guys can help you with that

 

i meant mark VIII,ithink thats eight?

 

VIII is 8, that's all I really got.

Except that your n/a diff will not like 650whp very much.

 

It'd be fine if you got no traction! But if you want to hook you'll distroy that thing!