What rear is this?

I was told 8.5 but the cover has an oil channel to feed the oil holes in the housing and though an 8.5 cover lines up with bolt holes it halfway covers the oil holes. I has strap type U joint and 3.08 gears.
Looks like 8.5 posi unit.

 

That is a Chevy center section with the oil feed holes at 3 and 9 o'clock positions. You do have a GM posi carrier....easily identified by the S spring.

You have to use a Chevy cover on a Chevy center section....you can not use the BOP cover.

 

OK, thanks George. Any idea why Chevy had different oiling? Are parts compatible? What do you think it came out of? It's in a 71 GS now.......


Bruce

 

Parts are compatible....most likely from a Chevelle/Monte Carlo.

Don't know why the different oiling but may be due to the different axle design. Chevy used C-clips while BOP used bolt-in axles.

 

But....this has bolt in axles (no clips).

 

Looks like it might be a 12 bolt(bolt at center bottom), that has been modified not to use the c-clips.Might be an Olds rear.o No:

 

Definately a 10 bolt.ou:

 

Sorry, I was wrong, the GM 12-bolt has 2 bolts at the bottom of the cover.

 

Appears to have "SD" stamped on the pass side axle tube.

 

I knew it!!!! Pontiac "Super-Duty".:laugh:

 

SD comes up as 3.08 posi Olds rear, late 60s.

8.5 or 8.2 is the question now. I thought 8.5 started in 1971?

 

IT is a 1971 1972 Olds cutlas / 442 8.5 corperate rear.

1971 1972 only...


Jim

 

The cover has oil groove only on passenger side. Does that help ID?

 

I wouldn't doubt Jim's (monzaz) ID. If he hasn't seen it before - probably nobody has.

 

Cover looks like this but not chrome.

 

Gave you the answer already. Yes that cover is on the 71 72 olds 10 bolt 8.5 rear. will have 4 bolts and 2 straps on the yoke. Bolt in axles and will use al lthe 8.5 gears in the aftermarket and gm. 28 spline axles 45 degree axle splines not like the 60 degree 1964-1970 8.2 axles that are 28 spline.

Take care, Jim

P.S. I am always learning STILL...I just know this one real well.

 

OK, thanks Jim.
Do you know why Olds oiled the side bearings differently than on the Buick 8.5?

 

I do not think anyone really knew if the oiling made any difference I say this because there are NOT oiling rear covers at all now...LOL. Just one of those designs that was deemed not necessary LIKE the job I use to have...LOL:laugh:

Ever part of GM was trying to figure out an edge and pretty much had some lateral ability to be creative anything to get a longer lasting service from parts.

I would chaulk it up to trial and error. NO real error just probably did not do what it needed to do as good as they thought.

Some 8.5 rear came with an internal oilier metal tab that came off the passenger upper cap bolt too. And that is not used either anymore. ??? Why? Again probably just did not make a huge difference in oiling for lengthening the bearing life.

Jim