Does anyone know if a 72 Delta 88 12-bolt rear end will fit a 71 442?

 

No , the mounting points are different and other things .

 

I'm having a hard time finding a posi unit for my cutlass 1971 10 bolt rear end. I want to keep the 10 bolt in there and change the gears and put a posi unit in there... Someone suggested that I may need to go to a 12 bolt rear end since I'm going to be be pushing about 550 hp... Any thoughts or suggestions would be very helpful...

 

Not only are the attachment points different, the D88 axle is several inches wider. Is there any reason why you think it would fit?

 

https://classicoldsmobile.com/forums...rear-ends.html

 

I thought the delta 88 was wider but a guy in the shop said that he thought it would... I figured I better ask the experts for help with my project so that's why I joined the forum...

 

You must be looking in all the wrong places as posi carriers for the 8.5" 10 bolt corporate rear are very plentiful. The 8.5" 10 bolt was used in various GM vehicles from 1971 up through the 90s and while the entire rear will not fit under a 71 A- body the carrier will fit in the housing. Richmond Gears web site shows all the vehicles that have compatible carriers that can be found in salvage yards, plus the aftermarket offers several different versions that can be found on Summit Racing, Jegs, and other web sites.

 

Also, maybe whoever told you to use a 12-bolt may have meant a Chevy 12-bolt as the Olds Type 'O' uses 12 bolts only on the inspection cover and secures its 8.5-inch ring gear with 10 bolts just like the corporate rear. The Type 'O' isn't really stronger than the 8.5 corporate rear.

 

Just get a 28 spline GM 8.5" posi, plentiful and cheap compared to the Type O.

 

Um...

Why are we even talking about a Type O axle? The OP's 71 has a corporate 8.5" ten bolt. The 72 Delta would have come with an 8.5" ten bolt also if it had a 350 or a 9.375" twelve bolt if it had a 455. Yes, the 9.375 is a "Type O", but not the A-body Type O and nothing interchanges.

 

Well, I brought it up because the OP had been advised to "go to a 12-bolt" and I wanted to make sure he knew the difference between a Type 'O' and a Chevy 12-bolt before he went shopping.

 

They also came with Pontiac 8.875 rears also. usually 400 350 4 bbl cars lowest HP cars got the 8.5 usually 350 2 bbl and chevy cars.

 

If you go to a Type C 12 bolt that would make sense. That is a Chevy 12 bolt and parts are very easy to find. This would be a Chevelle 12 bolt rearend. This would be a big improvement.

I can do one of those if you are looking for that. It is a non-posi but you can get all you need for a gear change and posi carrier for about $600.

Larry
lemoldsnut@aol.com