im keeping the 3.90 rear end, Can a manual driveshaft hook up to the 3.90 or is there some kind of special flange that i need for it?

 

bump

 

You can bolt a manuel driveshaft to the auto diff but you have to make 4 new hole because they don't have the same bolt patern.

Or yon can buy a manuel diff input flange and bolt it on your auto diff.

Eric

 

Best thing to do is a buy a manual bolt flange. If you "bore" the holes out to work, you'll either get lucky or wind up with a out of balance driveshaft and a lot more problems.

A manual bolt flange is just the piece that physically bolts to the rear with a large bolt (I think it's 27mm or something). It is what the driveshaft bolts to.

 

In my case i have not bore the existing hole but i drill out 4 new hole center between 2 existing hole!!

I run 5000Km with no problem and no vibration. But i will change my flange anyway just to be sure!

Eric

 

You are making 488 whp and i am sure you will want to make more power. get a 4.10 and a TII LSD. The 3.90 will just hold you back unless you are looking for high speed.

 

i have a friend with a 3.90 fd that **** is sick the 4.10 stock cant even compare. oh my car is going to be making 600 whp the only reason im going manual swap. does that flange have to be custom made or can it actually be bought somewhere?

 

You can buy it use on the 'for sale' section or directly from the dealer

Eric

 

you realize the 4.10 should pull harder than the 3.90 right?

 

That what I said

My FD was also automatic and i kept the auto 3.90 for a while until i swapped it for the 4.10 and at that HP range I wouldn't play games with the drive shaft/diff flanges.