70 F body 12 bolt WIW?
 

I'm posting prematurely because I don't have the codes at hand, but what would be the ball park value for this? It was professionally rebuilt by a driveline shop 3 years ago with new axles, bearings, seals and a new 3.31 ring and pinion. I'm pretty sure it's original to the car.

Is it pitted? Original backing plates? , is the front pinion seal shimmed so it doesn't leak? 3 years ago there was no 3.31 gear sets, are the originals worn?
There are plenty of peg leg 12 bolts out there. This a Eaton Posi?
A few factors to value IMHO having owned and rebuilt a few.
Easy guess if it's a nice posi with little pits u
Is $1600. Going over 2k unless it's missing from a TA, or Formula means there's new for 2500..
Market isn't great really as it's easy to build a 30 spline 10 bolt that's rugged. All IMHO..

I think the backing plates are original. No pitting, it's in very good condition. The truck pinion seal was installed correctly so no leaks. It is a limited slip and works well. I believe it is the original factory limited slip unit. It's quiet and smooth, no chatter or binding with the GM additive. I believe that the rear end only had around 9000 miles on it from new when I got the car 3 years ago and I've put another 6000 or so on it. At the time I had it rebuilt, 3.31 sets wee available from various sites online. I don't know where the shop got the gear from, I let them source it. That was around April 2021. So getting closer to 4 years now I guess.

Here's the best picture I have of the condition:

https://i.imgur.com/TefM2oWh.jpg

Original to your car?

If so I would think twice about selling it.

Is it a COV code? And if so, what is the date stamping? I might be interested, thx.

Think about fixing the lower sway bar bushing if not already done...

I would definitely keep the original rear for a desirable car they are only original once .. and iam not a purest .. just dont see any sence in going backwards by choice

Pretty sure it is. I've never checked the stampings. Crazy, I know, but since it's not a numbers matching car I didn't matter much to me. I'm just looking at all my options.

Hi Keith. Don't know what the stampings are. If I decide to sell I'll let you know.

That's an older picture. It actually has a different sway bar in it now with a correct bushing. :)

Ok, so it is a COX with date code 0622 and E for Eaton posi. It looks like there may be one or two more digits after the date code but I can't read them. So that's a 3.55 posi and the date code matches my car's production date so it looks like it's the factory rear end for this car.

https://i.imgur.com/xQNH6mhh.jpg

I think date code is 0622. O=1970,6=June,22 = day of month. I didnt know E= Eaton. Know I need to check mine. Thanks for sharing pics.

I agree with you on the date code. As far as the other stuff is concerned, if unruhjonny didn't object to my interpretation then I think I'm good. :)

A 0622 is June 22nd. There is no year indicator in the stamping. Looks like COX (application) 0622 (month and day) G (Chevrolet Gear and Axle, axle manufacturer) and there should be a number too indicating the shift next to the G, with an E (Eaton, posi) under it.

The COX rear axle is rare and valuable because it was only available for the 1970 F-body.

That's what I was afraid of. Now I'm inclined to keep it. That's the paradox. If it's rare, it's worth money. But if it's rare I want to keep it.

You should keep it you might regret you sold it in future. Just my tbought.

I say keep it. I kept mine (COZ) instead of sticking a 9” in it. Your 12-bolt is plenty strong enough for what you are throwing at it.

Nice clean original housing stamped COX & COZ housings are tough find,
then you throw in one dated to ones car & rebuilt w quality internals.... Duhhh!

This shows the G and the 1 pretty clearly on a rear I did in 2021. ( 3.31 gears) >> Keep your rear!!)
http://forums.maxperformanceinc.com/...5&d=1736055767