As I am about to order some parts from the U.S (to New Zealand) I thought I might add in a repro W27 alloy 10 bolt diff cover. It was while I was looking at Jegs for a new cover gasket that I realised my car's 10 bolt posi is most likely a 8.2" version as opposed to the 8.5" version which came out in about 1970. I have attached a PDF which gives a link to the W27 cover, the Jegs gaskets,a photo of 10 bolt diff without cover and images of my car's diff.
My diff cover has what appears to be the same bolt pattern as the W27 cover, 8.5" Trans Dapt 9052 and MrGasket 720-84 gaskets.It's also the same bolt pattern as the 8.5" diff image. But as you will see from the last 2 images my diff cover has the "cutaways" on the side of the cover as per the MrGasket 720-84 8.2" cover gasket.
I would like to know if the W27 will fit (what looks like) my 8.2" diff? The ebay config. thing says so but .... Also it would be good to know why the cover has the side cutaways and what the 8.2" or 8.5" size actually refers to.
The image of the 8.5" diff without a cover shows a widening of the flange surface and a couple of holes around the cutaway area.If anybody knows what the holes are for it would be good to know also.
Thanks very much in advance for your help.
Cheers

 

Please provide pictures of your differential cover
IF you differential is ALL original car. It will be a 10 bolt 8.2 Buick or Olds rear. Buick rear will only have lower webbing on the casting center. If it is a OLDS 10 bolt 8.2 it will have a vertical web from the pinion that blends into the casting on the passenger side of the pinion area casting.

NEITHER of these rears will handle the cover you PDF ed The 8.2 they are referencing is a CHEVY 8.2. The Chevy 10 bolt 8.2 cover and 10 bolt 8.5 Corporate cover are interchangeable. NOT the BOP 10 bolt 8.2. cover bolt patterns are different.

We sell a T/A race cover way better than the w27 cover and it is girdled to help support the bearing caps in the housing.

Jim

 

Hi there, the last 2 images (My Diff 1&2) on the PDF are photos of my diff complete with the cutaways.I am not sure what you mean by the "vertical web from the pinion etc" but I will get back under the car again and look/photo from the driveshaft side.My fault with the GM/Chev images as I didn't know that GM and Old's diffs are different.
The question now is does a later Oldsmobile 10 bolt 8.5inch diff cover like this one
http://www.ebay.com/itm/1964-72-Olds...-/350486962579 fit on the earlier Olds 10 bolt 8.2inch diff? I guess I will find part of the answer is if the cutaway area on my diff head is flat which I don't think it is .I think it will be curved as it follows the curve of the axle carrier so no go. There would be no point I can see in Olds making the cutaway cover if the mating area is flat!
Moving on the T/A covers are very cool and better quality/useful than what I was looking at.

 

Hi again, the correct product to fit my car's 8.2" posi diff are these ones below, correct?