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I have this type "O" rear differential currently. I don't know gearing, but it is an open dif.. After getting it all clean and shiny, the shaft seal is leaking. I don't mind fixing, but I am wondering if anyone has thoughts on donor cars with GM rear difs with a posi and cruising gears?
I would like to stay in the 1968-72 range.
I would like a posi type.
I will mainly be cruising and "occasionally" melting rubber.
Any advice on gear kits with posi that might bolt up right for the current setup instead a whole new rear axle assembly?
1968 Oldsmobile 442 Convertible with 455 and TH375.
Yeah, that new Yukon posi is 3/4 the price of that rebuilt Type O, trust me🤑🤑🤑. I am doing that exact set up this Summer to replace my 2.78 open, just need the bearings and seals.
Some Cutlasses that were built in Canada came with the Chevy 12 bolt rearend , you can get every thing you need to build the 12 bolt Chevy that you have from the after market vendors ,
No, you don't. The O-Type has a 12 bolt cover, which is not what your picture shows. That is obviously a 10 bolt rearend, maybe a 71-72 8.5" 10 bolt or maybe an 8.2" 10 bolt. Need some views of the side of the center section and/or casting numbers for better identification.
Both of the above 10 bolt rears have a lot of aftermarket parts available; you just need to determine exactly which one it is.
No, you don't. The O-Type has a 12 bolt cover, which is not what your picture shows. That is obviously a 10 bolt rearend, maybe a 71-72 8.5" 10 bolt or maybe an 8.2" 10 bolt. Need some views of the side of the center section and/or casting numbers for better identification.
Both of the above 10 bolt rears have a lot of aftermarket parts available; you just need to determine exactly which one it is.
Appreciate the info. Here is what I have found:
Axle tube is stamped "CB" "226W"
My conclusion...from the manual:
Likely geared 3.36
Made Feb 26 in Warren, MI
I am guessing an 8.5? I need to replace the pinuon shaft seal and need to determine which seal to purchase. Does it matter which type housing 8.2 or 8.5, or are all pinion shaft seals the same flavor?
The placement of the casting numbers on an 8.2-inch 10-bolt varies
by year and model. When you decode these numbers you can
conclusively identify your axle.
Sorry if I'm confused, but are you talking about the axle in your first photo? That's clearly not a "Type O cover", since it has the inverted "V" notch and only ten bolts.
Sorry if I'm confused, but are you talking about the axle in your first photo? That's clearly not a "Type O cover", since it has the inverted "V" notch and only ten bolts.
You are clearly correct. Thank you for clarifying. My apologies.
If you have an Oshawa built car it's probably the original rear. Why not just put a posi in it? I would think there are more options for that rear than a type O. I have a 3.42 with an M20 and I think it's a good match. I don't know anything about automatics though
Sorry, no. Oshawa cars got the Chevy TWELVE bolt axle with the 8.875" ring gear, not the 8.2" ten bolt.
Got it. Thanks
A quick google search implies (because I admittingly don't know) that an 8.2 posi is fairly easy to obtain and most people will never need the strength of a 8.5 or 8.875 for their daily driver
To clarify, Canadian (Oshawa) built cars came with the Chevy 12-bolt in '68-9. US cars got the Type O. Available ratios differed between the two; my understanding is that the 12-bolts were commonly equipped with a 3.07 and the O's with a 2.73 or 3.08. In either case Posi (Anti-Spin) was optional.
To clarify, Canadian (Oshawa) built cars came with the Chevy 12-bolt in '68-9. US cars got the Type O. Available ratios differed between the two; my understanding is that the 12-bolts were commonly equipped with a 3.07 and the O's with a 2.73 or 3.08. In either case Posi (Anti-Spin) was optional.
The standard and available axle ratios are listed in the SPECS booklets and differed between the two axle types. In any case, this is not relevant to the OP's non-original Chevy 10-bolt that is the subject of this thread.
In any case, this is not relevant to the OP's non-original Chevy 10-bolt that is the subject of this thread.
Comes under the heading of info that might be useful if OP is still up in the air about replacing his current unit, as he appears to be. Good referral to the Specs book!
