I can get one cheap, its almost exactly the same width as my 2.73 open 7.5 and it even has a nice painted rust free housing, new brakes and the right 5 on 5 lug pattern

It's HUGE in the center and it's a 2.92 or 2.93 gear with an open diff and 12 bolts on the cover with some beefy looking axles and spider gears but the carrier looks kinda small to me for such a big rear...

Does anyone make a locker or posi for this beast???

The gears are a little step up from 2.73 and I could live with that but Id need a posi or locker to make the swap worthwhile

I already have adjustable upper arms on the Ninety Eight and the mounts seem close enough it might bolt in???

Im sure Id need to shorten the drive shaft too...

Anyone got any info on this, thanks...

 

Got some measurements and I think i could make it fit...

The upper ears are roughly 12.5" apart on the 12 bolt and 11.5" on the 7.5", close enough...

The lowers are 45" apart on the 12 bolt and 43.5" on the 7.5" rear, maybe need some double adjustable lowers...

Spring perches are 40" apart on the 12 bolt and 35" on the 7.5" rear might work as is but easy to move these...

They both use the straps for U joint but I think it might be a different joint, should work with a conversion joint or a new U joint flange when shortening the drive shaft...

Roughly 3/4" wider per side over all, should work...

Im pretty sure I can make this bolt in

I guess I need a factory posi carrier though, anybody have one

This is a nice car with a pretty stout 425 with headers and nice exhaust ect...and TH400, I can see it getting more power...

That 7.5 just seems too wimpy to me

 

PM monzaz (Jim). He should be able to help you find a posi.
Are you sure it has a 12 bolt cover Steve? I thought they used the Pontiac rear with a 10 bolt cover and 12 bolt ring gear. If it's one of those, I have a complete 3.23 posi, drum-to-drum in my garage. Not gonna make it to Byron this year, though.

 

It's 12 bolt cover with what should be a 12 bolt ring gear, Id have to check that

It's not the little A body O type though, this thing is heavy duty

If you were closer Id be interested in the Pontiac rear but this is just a cool driver, nothing urgent it goes good for now even with a 2.73 weak suck 7.5 open rear...

 

It's not a direct bolt-in,but I'm sure you could fab it in there.

 

It's not just the spacing on the mounting ears, it's the angle. If the angle is wrong, the suspension arms will bind. Parts for the 67 axles are even harder to find than for the Type O.

More to the point, 8.5" axles for these cars are a dime a dozen. The 1991-96 Caprice axle is a bolt-in and can be had with disc brakes. All the 91-96 cars used the 5 x 5 bolt circle. Note that the wagon axles are wider than the sedan axles.

 

Joe has a good point. Most of those caprices came with disc brakes 3.08 or 3.23 gears, AND they have 30 spline axles.

Too bad they're c clip auburns. A definite step up in axle strength though.

 

Well I can't find one, much less a dozen for a dime

J has a wagon rear that's too wide and a couple A body rears with the small bolt circle crappy gears and the little lug studs...

The big car type O 12 bolt has huge gears and bearings with 31 spline axles

I can order 4 rod ends and make my own double adjustable lowers with some spare roll cage tubing...

Too bad GM couldn't have built the car right in the first place

 

Haha, yep. I don't feel bad one bit for GM stockholders that didn't see the writing on the wall 25 years ago.

 

Hmmm... sounds like maybe it's a 9-3/8" Olds 12-bolt. But I thought they weren't available until the '68 model year. Very hard to find a posi or decent gears for that rear.

 

I could live with the gears, 2.93 is fine for a driver with the TH400...

Im worried about burning up my brand new white wall and blowing the spiders on this open 7.5 doing mini burnouts, and occasionally HUGE ones, around the hood here in my ghetto cruiser...

The cops dont like it thats fo sho!!!

I got the ported Ka's from Luke, and he got em from you, they work good in this old boat with some new valves and springs

Besides I want to go to Byron with it and bracket race

 

I wondered if those were my old ones. Funny you should mention boat - I bought em from a jet boat guy who got sick of blowing up 455's
Did you notice the little set screws on the exhaust bolt holes? I guess his aluminum log manifolds kept loosening, too. They looked like nice heads to me, but I never ran them. They had some unknown double springs and wierd orange anodized aluminum retainers when I got them. I take it you didn't use them

Sorry I will miss the Byron race this year. I really wanted to be there, but my stepson has end-stage stomach cancer. Not much time left, so I can't leave my wife alone to go racing

 

Yep I took the set screws and oil drain fittings out and had new valves, retainers and springs put on, the new guide liners were installed already but not finish machined...

They run good on my junk

Sorry to hear about your stepson

 

That's the only thing that I don't like about this swap, is the 5x5 bolt pattern. I'm willing to bet that the disc brakes require at least a 16 inch wheel

 

Uh, the OP has a 1984 Ninety Eight, which already has the 5 x 5" bolt circle. Also, the stock Caprice 15x7 wheels clear the disks just fine, since the fronts are the more severe clearance problem. Again, not all 15 x 7" wheels are created equally. The stock Caprice wheels have a contoured center disk with a deep flange for the lugs that allows them to clear the disks just fine.