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monzaz · 07-08-2008, 12:48 PM

Yes you are totally correct. 8.5 10 bolt corperate olds rear. 725 726 carriers.

I think the 725 was the 2.73 -4.56 and up 3 series
the 726 was the 2.41-2.56 carrier.

It could be vise versa on the 725 726 thing but those are the correct numbers for the carriers

IT is not original to a 1970 UNLESS they started to put these into 442 late in the 1970 year run? The drive shaft would have to of been shorten by about an 1" making this a NOT so easy swap. SO either someone went through some trouble or it did come factory.

I have listed that 1971 1972 was the years the corp 8.5 was used. BUT you know how that always goes... If you run out of diffs you use what yah got deal.

The yoke will have 4 bolts holding 2 flat arced straps over the u-joint cup for an 8.5. all other BOP rears were u-bolt.
A chevy cover has the eyebow cover (axle bearing oiler cover) that has a crease across the whole cover from left to right.
the olds cover had only 1/2 the eyebrow. Until the 1973 era then everything withthe covers got messy...lol. Now they just use one cover and it is smooth with ring gear buldge.

Just some extra info... Chevy a-body cars 1965-1972 with c-clip retention were never 8.5 they are all 8.2 1973 was the first years for chevy using the 8.5 in a A-body car. Camaros started in the 1970 2nd gen cars. Even Pontiac ran the 10 bolt 8.2 to the end of the 1972 muscle car era...NO 8.5 in thier cars either. BUICK and OLDS were the ones with the 8.5 bolt in axle rears 1971 1972 The buick 8.5 has a couple other tell tail signs of 8.5 and the cover for the buicks LOOKS almost like the 10 bolt 8.2 BOP covers. But that is another forum...lol.

Hope this helps.

You can buy any gear ratio from any 8.5 axle 1970 -2008 and it will fit. The posis can be used from 1970 -1987 cars and even trucks from 1974 -1989 28 spline in this rear.

We use 30 spline moser custom axles and 30 spline aftermarket posi units to make these rears as good as chevy 12 bolt rears.

I like them alot I would keep it if your not looking for an all out original car.

07-08-2008, 12:48 PM	#3 (permalink)
monzaz Senior Member Join Date: Jul 2006 Location: Richfield, Oh Posts: 118	442 axle ID Yes you are totally correct. 8.5 10 bolt corperate olds rear. 725 726 carriers. I think the 725 was the 2.73 -4.56 and up 3 series the 726 was the 2.41-2.56 carrier. It could be vise versa on the 725 726 thing but those are the correct numbers for the carriers IT is not original to a 1970 UNLESS they started to put these into 442 late in the 1970 year run? The drive shaft would have to of been shorten by about an 1" making this a NOT so easy swap. SO either someone went through some trouble or it did come factory. I have listed that 1971 1972 was the years the corp 8.5 was used. BUT you know how that always goes... If you run out of diffs you use what yah got deal. The yoke will have 4 bolts holding 2 flat arced straps over the u-joint cup for an 8.5. all other BOP rears were u-bolt. A chevy cover has the eyebow cover (axle bearing oiler cover) that has a crease across the whole cover from left to right. the olds cover had only 1/2 the eyebrow. Until the 1973 era then everything withthe covers got messy...lol. Now they just use one cover and it is smooth with ring gear buldge. Just some extra info... Chevy a-body cars 1965-1972 with c-clip retention were never 8.5 they are all 8.2 1973 was the first years for chevy using the 8.5 in a A-body car. Camaros started in the 1970 2nd gen cars. Even Pontiac ran the 10 bolt 8.2 to the end of the 1972 muscle car era...NO 8.5 in thier cars either. BUICK and OLDS were the ones with the 8.5 bolt in axle rears 1971 1972 The buick 8.5 has a couple other tell tail signs of 8.5 and the cover for the buicks LOOKS almost like the 10 bolt 8.2 BOP covers. But that is another forum...lol. Hope this helps. You can buy any gear ratio from any 8.5 axle 1970 -2008 and it will fit. The posis can be used from 1970 -1987 cars and even trucks from 1974 -1989 28 spline in this rear. We use 30 spline moser custom axles and 30 spline aftermarket posi units to make these rears as good as chevy 12 bolt rears. I like them alot I would keep it if your not looking for an all out original car. Last edited by monzaz : 07-08-2008 at 12:56 PM.