What's the going rate for a 10-bolt A-body rear? It's a clean core, 3.31 gears, open differential (non-posi). It came out of a '71 Buick Skylark GS350 car.

 

Recheck the ratio.They did not make a 3:31 ratio for the 8.5" 10-bolt.They made 3:23's & 3:42's,but nothing in between those.
It might be an 8.2" 10-bolt.Those could have 3:36 ratio,but the last year they put that rear in the Skylark/GS was 1970. There is always the chance that the rear was swapped in the past. If you can,post some pictures of it,& I'll identify it.

 

Well alot depends on housing conditions , gear ratio and internal condition...BUT being a 10 bolt 50-150 all mostly depends on if you can find the right person at the right time.

local sale would obviously be a plus since shipping will be almost as much as the rear. If you have pictures of the rear cover area we can ID the rear and maybe help you have all the info to sell the item easier.

Jim

 

ok, so the 3rd pic is a 8.5 but not built by Olds. Mine looks like that one. This is the good one to have right?

 

Is it in the car in your signature? If so,it should be a 71-72 8.5" 10-bolt.If it has a cover like the 3rd one pictured,then it should have a large letter "A" at the top of the pumpkin.It's a keeper.

 

yes to both. It only has one rib instead of two. I can't remember if it had an "A" on the top or not. I'll try and feel around tomorrow for it. I have yet to find the codes on the tubes yet. I painted it and can't seem to find anything that even resembles letters or numbers.

 

Go to 442.com to get an idea of price, or www.BCA.com for more info.

 

PLEASE...post a picture of the rear cover area and we will be able to clear up exactly what you have.

IF you only have a lower web on each side connecting the pinion area to the tube area and NOTHING on the top parallel to the lower webing THEN you have a 10 bolt 8.2 68-70 rear in the car. PICTURES...please. then we will get it exact for you. Jim

 

sorry it took so long.

 

T Bell,
That is a 71-72 8.5" 10-bolt rear.That housing is the "A" casting.That's a keeper & worth building.

 

But it only has one rib on the bottom, like a 8.2

 

If you look above the axle tube area,you will see another rib.It is shorter,but parallel with the large one.

 

Second vote of confidence...IT is a 10 bolt 8.5 Buick style. The cover will look like a 8.2 but really is not and will NOT interchange with a 8.2. Thew parallel webbing will be smaller above the lower webbing. AS as stated will have the BIG 'A' cast into the middle of the casting between the upper control arm bosses. Plenty of parts available in the yards and the aftermarket world for this rear.

Good luck on the build. Jim

 

I found the A and the smaller web (laid on the ground this time). What kind of power can one of these handle. I was going to swap in a 9 inch or 12 bolt. Plans are for atleast 400 up to the wheels.

 

No need to swap rears for that power.In a car like your 72,that rear,rebuilt,with stock 28-spline axles,NO special parts like aftermarket axles or girdle cover,can handle high-11 sec ET's. Upgrade to aftermarket 30-spline axles & such,& it will handle much more.

 

Ditto on the Brian advice. You will be fine with the 8.5 and you have the bolt in axles to boot if anything does decide to break.

I race with the same 10 bolt 8.5 rear and am into the 10.90 YES it is only a MONZA/ starfire h-body, but it still leaves hard and has to do so to get the numbers....lol


If you have money to throw...Then hey get what you want we are just giving you the best advice we can for you to work with.

Then with the money you save you can afford one of these nice T/A covers and maybe even some NEW brakes....LOL

Take care have fun... Happy Holidays to everyone!

Jim

 

No, no. I thought that the strongest rear end was the 9inch. I'm excited about being able to use what I got. And one of those T/A covers from you Monza is in my future. Thanks for the help guys. I guess I can POR15 it instead of the cheap paint now.

 

Everyone always think the 9" is so strong...??? It is a 10 bolt like any other 10 bolt.

IF you want a strong 9" you have to use aftermarket center section and parts or it is NO better than any other Stock 10 bolt in the world.

The reason everyone uses this rear is because it is easy to weld stuff to like mounts etc even upper control arm mounts. But that same housing that makes it desirable for mods is the weakness too. Sheet steel housing just can not handle the twist...that is the reason for all the mods of the housing.

Reason 2 for the 9" popularity is the ability to remove the front third member to replace it with another in a different ratio. circle track is a great place with the varity of 1/4 mile to 1/8 miles tracks etc. Same if your going from a 1.4 mile or 1/8 mile drag too.

The 5th bearing does give it more strength from pinion deflection...but the pinion shaft in a 9" (1.313) also smaller than a 7.5 (1.438) Also the front pinion support plate gives way before the deflection of the pinion causing more issues in drag racing and hard launches. SO if you going to look at apples to apples and oranges to oranges do not compare after market FORD to stock GM rears...Which I will still take the GM rear...lol. JIm

 

T Bell......
Out of curiosity, how wide is that rearend, backing plate to backing plate? 54? 55? 56"?

 

It's 55" best I could measure. Why do you ask? And Monza, I was under the impression that a 9" was better because of the 9" carrier. Thanks for schooling on my rear and busting the myth about Ford rearends. So now I can scrounge the yards for a posi to rebuild in stab in. When'd they quite making the 8.5?

 

For a posi I would just order one from Brian Trick above. For gears they are everywhere. My GM 3.73's came from a mid 90's suburban.

 

My Buddy has that same rear axle and I was hoping to pick it up from him for 75 bucks and stuff it under an 80's cadillac. It will fit. Thanks.

 

Yah, it unfortunately is just another myth like all the rest of the garbage that is jammed down our throats. Like Music on the radio. If that is what is fed to you again and again... you tend to start thinking that is all there is.

A lot of great engines, transmissions and rear diffs out there. If you take the time to properly build any of them they ALL will do the job very well. INCLUDING that darn 9".

 

They are still making the 8.5",so they must be pretty good.I wish they would have put that under my wife's Envoy because there isn't too much goodies available for that yet.That will be getting handed down to me,when I get her a new vehicle,so it will get 3:73's & whatever the best unit is at that time.The 3:42's don't quite cut it in that thing,& I think I can get better mileage with the 3:73's.We'll find out.Sorry to get off-topic.