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I have a set that I bought for my old 70 Monte Carlo that never got installed. IIRC - They were Richmond gears and I;ll have to dig them up. Pretty sure they would also fit the Later GM rear but you may want to confirm that. Let me see if I can get some more details for you tonight and go from there. If all looks good, i'll take $75 plus the ride.
 

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Discussion Starter #3 (Edited)
I have a set that I bought for my old 70 Monte Carlo that never got installed. IIRC - They were Richmond gears and I;ll have to dig them up. Pretty sure they would also fit the Later GM rear but you may want to confirm that. Let me see if I can get some more details for you tonight and go from there. If all looks good, i'll take $75 plus the ride.
Cool just let me know what you find. I don't care about the ABS reluctor so those should be fine AFAIK?
Got the rear axle still from the POS RMW I bought. Figure do the gears now/swap axles before the new engine goes in.
I really do not like the 2.93 gearing!
 

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sorry for the Delay....forgot to get a pic last night. It's been a while since I got these and remembering now that I did have a shop install these in my Monte but only had them in there for a thousand miles or so. I wanted to go with a ratio that was a little steeper instead and just saved these.

The box has the Richmond Logo but actually think that was from the replacement set I got. I just counted the actual teeth on the gears and the Ring is 39 and Pinion is 11. So I was wrong on the ratio as they are actually 3.54. They look perfectly fine and there was no problemwith them i just "wanted" something differnt for my heavy Monte.

I "believe" these are actually made by DTS. On the Side of the Ring gear is engraved with "DTS 0627-2 3620 MADE IN USA". If interested please make sure these will fit your Rear. As I said, these were in the Corporate GM 10 Bolt that is in my 1970 Monte Carlo and "think" they would fit. Let me know if you need more pics and we can talk more then...Thx.
 

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Discussion Starter #5
Can you measure the ring gear? I'm no expert but looking online shows 8.2" 10-bolt for a 1970 Monte Carlo.
 

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While nothing is in stone, and there are exceptions, typically the 8.875 and the 8.2 chev diff was in 70 and the corporate 8.5 71 and up.

I know of no 3.55 (rounded up) corp 8.5 but that is a 8.2 ratio.

The 8.2 pinion spline is 25 teeth iir
The 8.5 is 30 teeth , for sure.

The 8.2 has 3/8 -24 ring gear bolts
The corp 8.5 has 7/16-20 LEFT HAND

Hope this helps

EDIT , there is no step on the pinion in your picture for the short crush sleeve that the 8.5 -8.6 uses.
The 8.2 and 8.875 use a long sleeve that goes down to the rear bearing.
 

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Cheap off brand

https://www.ebay.ca/itm/CHEVY-GM-8-6-10-Bolt-Gears-Ring-Pinion-3-42-NEW/371964743275?hash=item569ad38e6b:g:U9UAAOSwVL1V~jeL:rk:18:pf:0#shpCntId


OE GM used

https://www.ebay.ca/itm/OEM-GM-CHEVY-10-BOLT-8-5-RING-PINION-3-42-GEAR-RATIO-GEARS-SET/113311606800?hash=item1a61e5e810:g:fW8AAOSwTitbxQsz:rk:17:pf:0


You can also see in those pictures that neither the cheap new gears for ABS or the used non ABS gears look like the 3.55 pinion 4DoorSS has.



Now to add a personal note, unless you are going to Bonneville, my I suggest you consider 3.73?
 

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Thanks for all the extra info guys. The more info the better so we can make sure to have all the info possible.

A little background on my Monte, I bought it over 25 Years ago and it was bone stocker with a 400 SBC, 2 barrell carb, Auto trans and a 1 legger rear. At some point I picked up a 10 bolt Posi rear to swap in that may have been out of a Chevelle. Whatever car it was from bolted right in.

That was a good point on the Pinion splines and just counted those and there are 30 splines. Also, measured the Ring Gear and it is 8.5" across and the back side has 12 bolt holes to mount it to the Diff. Babywag - if there is anything else I can provide or more pics, please let me know. I sure don't want you to get something that wont work for you.
 

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has 12 bolt holes
Soooo, that would sound like you have a 12 bolt Chev 3.55 (8.875) ring and pinion there.
I didn't mention the 12 bolt pinion spline because I ASSumed you had a 10 bolt gear gear
Quite saleable, just not in a late 8.5 ?

I wouldn't have linked other gearsets for sale, or suggested other ratios , if yours was going to fit his car.

Does your Monti, now, have 12 bolts on the cover ?

If you are positive that the "10 bolt posi" you bought had a 10 bolt cover and this 12 bolt ring gear, that is the weirdo corp 8.875 ( least that is how I refer to them).
They were around in the 60s in some Pontiacs and 70s in some full size.
My 78 caprice wagon had one
 

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Well, (sheepishly) I feel silly as heck. Looked under the car and YEP....it's a 12 Bolt....Doh! I am excited about the fact I have a 12 bolt in there instead of the 10 bolt but this explains a lot about that ratio. When I measured the Ring Gear, I sort of guesstimated the size due to how the ring tapers outward. In any case, sorry Babywag for all the confusion and back and forth. Good luck in your search.
 

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Discussion Starter #11
Cheap off brand

https://www.ebay.ca/itm/CHEVY-GM-8-6-10-Bolt-Gears-Ring-Pinion-3-42-NEW/371964743275?hash=item569ad38e6b:g:U9UAAOSwVL1V~jeL:rk:18:pf:0#shpCntId


OE GM used

https://www.ebay.ca/itm/OEM-GM-CHEVY-10-BOLT-8-5-RING-PINION-3-42-GEAR-RATIO-GEARS-SET/113311606800?hash=item1a61e5e810:g:fW8AAOSwTitbxQsz:rk:17:pf:0


You can also see in those pictures that neither the cheap new gears for ABS or the used non ABS gears look like the 3.55 pinion 4DoorSS has.



Now to add a personal note, unless you are going to Bonneville, my I suggest you consider 3.73?
I thought 3.42 would be easier to find used.
I'd be open to 3.73 but have heard some folks needed driveshaft work.
Budget wise there isn't one, too many other things that require my $ right now.
So just looking for a little bang for little $. Car won't ever see track/strip time.
 
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