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Actually yes and no...outside yes across the teeth, on the inside I measure where it meets the carrier..With the large outside diameter I'm thinking either 9.375 Olds or a 3/4 Ton pickup...If it's even GM..There is a possibility of a Dana, Chrysler, or Ford...all had rings around that size..best ...

What is the outside and inside diameter of the ring? 74 Olds could have had 2 different 12 bolt rings, if that is what it is for...either 9.375 or 8.875...8.875 had 30 spliner pinion so I'm, guessing the 9.375 but I didn't think anybody made aftermarket gears for those. If they are for the 9.375 I'd ...

Yeah I don't think .040 would hurt too bad...better than the .110 that I would have to open up an older 8.5". I suppose I wouldn't even have to go that far as the 31 spline axles are only 1.315..so maybe .020 or so..

I will have to ponder on that newer carrier thing...we have no such thing as a ...

The flange height was the same as the 72 10/12 I have at 1.980 from the end of the bearing hub...Looks to be identical to the 72 version as far as dimensions go...smaller spider shaft and larger/longer pin bolt.

Here is a bit of interesting info for ya..the guy O got this carrier from said he had ...

Jim,

Numbers when you get a chance would be perfect.

Just out of sheer curiosity how much is a new open carrier? I'm sure it is out of range for what I want to do but.... Do you ever get any in used?

Thanks again,

Chris Vaughn

I am pretty sure this is for a 65-70 Pontiac 10/12 but...
Casting number ED30153 (153 only on Ring side)
Other casting marks..."ARMA STEEL"
Ring stamped 41-15 GM 1 70CY (no pinion but 41-15 = 2.73)
12 7/16 Bolts (haven't check but I assume LH thread)
Spider gear (differential pinion whatever) pin ...

Jim you nailed most of it...now I just need some numbers...What I'm trying to do it build a frankentube...
I want to use a 8.5" ring and pinion (due to ease of finding gears) with a 31 spline axle from the odd ball Olds/Pontiac stuff I have. I'm not too worried about the internal gears fitting ...

Let me start with what I think I know...
Only 2 carriers, 2.56 and down and 2.73 up?
From 71-89 all 8.5' used the same 28 spline axles (some bolt in some C-cliped)
90 to 00 had 30 spline axles with the same carrier bearings as 71-89 (all c-clip)
00 to current had 30 spline axles with bigger carrier ...

Did some tear down today on what I thought was a 8.875 Corp...here is what I found:
Carrier Bearings LM603049/LM603012
Outer Pinion M88048/M88010
Inner Pinion M804049/M804010
Carrier casting 250 (2.73 ratio, eaton style posi)
Housing casting 480633 (From a 72 Chevy wagon)
Axle code 7D P293 (7 may ...

I think your correct about the 3.42 being as steep as they got from the factory. I need to open up a couple of the other rears I have and see what they are.
I may have hatched another plan however. A little back ground on the project may even help you understand why I am attached to these odd ball ...

I have a Oldsmobile 12 bolt rearend (actually i have 3) 1 is from a 70 Delta, 1 in a 72 Delta, and 1 in a 73 Wagon. This is not the 10 bolt ring version both cover and ring have 12 bolts. Housing casting number is 383300, carrier is a casting of 698. Also on the carrier is a "GG" a "387" and a "2 ...