I read that the rear end bolts right up with the drivetrain but I wanted to make sure there wasnt anything else that needs done. I found a 98 rear end out of a firebird that has posi, disk brakes w/ cross drilled/slotted rotors for 250 and was gonna jump on it.

 

If you do a you'll see that the biggest issue is the e-brake cable - there are several ways to attack it, you'll see them all with some research.

Some swap out the proportioning valve to accomodate for a different fluid pressure requirement of the rear disk vs. drum, some say leaving the stock valve works fine.

Depending on your car, might have to remove and use the brake hardline and T fitting from your 3rd gen rear - some of the 4th gen rears had different sized fittings between the car and the axle.

That's about it.

 

the diff is 2 inches wider...your tires will stick out more..

 

Well thanks for the input and I do some searching before I posted another thread on this. The old threads say that with the 4th gen rear end my tires will be more or less flush with the fender. I didnt see the problem about the e-brake though I guess I over looked it. So let me ask this is a good buy? My rear-end has a worn out posi-unit and leaks. I also wanted a different set of gears and I wanted to get disks all around.

 

16" wheels = flush

15" wheels....I've never looked at the backspacing

The 2 e-brake cables can be spliced together, or, I believe it is, Hawk's make a new one with 3rd gen on one end & 4th gen on the other.

 

I have 17x8 rims not stock

 

Also on some of the old threads they said you could buy a new 3rd gen cable the longer of the two lengths and that all was well??

 

Depends on your backspacing then.

My 17" x 9" (before I had them widened to 11") had 5" bs & were in maybe .5", on my stock 9-bolt axle.

So on mine, 2" wider would push them out about 1.5", past the fenders.

 

It wouldnt bother me if they stuck out a lil bit. If i had know that you could swap rear ends and get widers rims I would have done that the first time. So eventually I would get a pair of 17 or 18x9 or 9.5 for the back. Do you think it is something I should invest in?

 

1.5" out PAST THE FENDER, is not "stuck out a little bit". You could stand on top of that tire, beside the fender!

And I'm confused. You just said a few posts ago:
Yet just now, you said:



On a 4th gen rear end, whatever wheels you have or get...You'll need wheels with the modern offsets like the 4th gen & C4/C5/C6 wheels.

 

Sorry about that I was confused myself. I understand what I would need for the tires. I didnt realize the offset differences, or that I would need that 4th gen rear end stuff. I tend to over look things. Anyways they didnt sell that size for the 3rd gen but i think they did for the 4th gen. If its not a good idea I'll just buy the cowl hood I was planning on since I will need clearance for the engine I have planned.

Also I am pretty sure but not postive that the tires have the backspacing as the 16x8 tires i took off.

 

Ed Miller makes custom parking brake cables for the LS1 (98+):

http://www.flynbye.com/catalog/i153.html

Aside from the parking brake issues, you'll have to consider the combination valve and speedo gears. The following link may provide food for thought:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

I know that if the rear end gears are change the speedo wont register correctly. I did already see that the valve should be replaced but could work with the stock one.

 

While the drum/disc combination valve will work, remember that GM designed three valves--disc/drum, disc/disc, and 1LE, each I believe with increased bias--so the correct valve for your application is a wise choice, IMO.

JamesC