lil_no

What's a reasonable price to pay for a complete 68 "O" type 12 bolt posi rear end with 31 spline axles and 3.42 gears? It's been in storage for some time so I'm thinking it will need to be cleaned up and rebuilt. Gears look good and there is some pitting and rust on outer housing.

droptopron

I got the same rear with a 3.23. it sat for a while but I stuck it in & ran it. A month or two in the front pinion started leaking but no problems otherwise. I paid $600 for it.

OLD SKL 69

There's a member on here named Monzaz. He rebuilds these for a living. You can send him a PM and I'm sure he could give you an idea of what a fully rebuilt one would cost and what you should pay for a used one.

lil_no

Thanks guys. I appreciate both of your input. I have chatted with Monzaz in the past because I was looking to buy a posi carrier from him. Just weighing my option and trying to decide if it's better to buy this unit with a posi already or build up the peg leg I currently have. PM'ing Monzaz isn't a bad idea for getting a round about idea on what a used one is worth.

Thanks again.

oldsmobiledave

The used one is over 40 years old & likely will need to be rebuilt anyways. Buy new parts & do it once & do it right.

Aceshigh

IIRC

I sold my 1970 "O" rear end with a 2.78 open carrier to Monzaz 2 years ago for $200.
I was just upgrading to a Chevy 12 bolt 3.73 posi because it cost too much to upgrade the fake 12 bolt.

jensenracing77

fake 12 bolt? i seriously doubt that Oldsmobile engineers had any thought of deception when they made the 12 bolt cover on a 10 bolt rear end. my rear end guy tells me that stock for stock, the O type is much stronger than the 12 bolt. i don't know if that is true.

monzaz

Hmmm. Yah can not exact say that would be true.

12 bolt olds
strengths- BOLT IN AXLES (31 way strong) - Big inner bearing and pinion shaft
Heavy cased posi unit with strong steel clutches.
Weaknesses - small outer pinion bearing and 27 spline shaft for yoke in put- 28 spline axles- ring gear surface area-smaller aftermarket supply of parts.

12 Bolt Chevy
Strengths - 30 spline axles- Larger ring gear diameter- 12 bolts holding the ring gear stable -large 30 spline pinion large inner and outer pinion bearings- superior EATON clam shell posi unit - steel clutches higher clutch preload spring rating- many many aftermarket parts
Weaknesses - C-clip axles (drag race application) small size u-joint (factory) - Housings are expensive - expensive because of aftermarket and restoration wants - Stock tapered c-clip axles
STOCK FORM
> for the street I would say flip a coin....
> if were talking stock to stock 31 spline olds really in the day was the rear to do the job for the track. STOCK FORM...
> Aftermarket parts add on 12 bolt chevy will take the cake for the street and strip.

monzaz

Like any commodity the want of that product is what drives the price up.

For restoration purposes this rear is high in want...

It all depends on how BAD you want it VS how bad the person needs to sell.

You have to make points to the seller as to why you should pay less...It is Used...Period. Condition is truly UNKNOWN till you get iti in the car.

Start with spider gears condition and ring gear condition if they are looking heated up or have some wear the whole rear is probably not far behind in the same condition.

I wish I could just throw numbers at you-

A price for ME to buy compared to a price for you a guy that will actually USE the rear will always be higher.

MY opinion -
If the rear housing is in good condition and the tube code matches the gear set all the parts are in good looking condition, I would buy the rear for 400.00-600.00 (for a recondition and re sale price)- YOU could buy it for as much as 1000.00 if your going to actually USE the rear under your car and as much as 1300.00-1400.00 IF YOU REALLY NEED THIS to complete a 100 point restoration car or more...???

See what I mean HOW BAD DO YOU NEED IT?

507OLDS

....and because you got a real good deal on that 12-bolt Chevy.You know what it would have cost to build that from scratch.About twice as much as what it would have cost to upgrade your existing O-axle.Yes,once in awhile,you can find a true deal.Someone is hard up for money,and needs to unload something,therefore the buyer gets lucky.

As far as the value of the 31-spline 3:42 O-axle posi rear,$700.00-$800.00.The only thing I would be concerned about is the axle shafts.As long as the surface under the axle bearings is good,then I'd go for it.The only thing is you would need to remove the bearing from the shaft itself,to see that area,which obviously involves taking the axle apart,thus owning it.The 67-69 shafts,with the RW507CR style sealed bearing,were notorious for breaking down under the bearing.The remedy is an aftermarket set of shafts,made with better material.

lil_no

Thanks Monzaz, 507OLDS, and everyone else. The information given is very helpful and is exactly along the lines of what I was looking for. I understand price is based on supply and demand and mainly what someone is willing to pay. I assumed the price should be in the $600-900 range depending on condition especially since it been sitting for sometime and the unknown fact of whether or not there are any issues.

Thanks again for the replies and this give me food for thought. I may go check it out this weekend if I can get free from the ball and chain since it's mother's day weekend...