Going on a road trip sunday found a 68/72 chevelle 12 bolt posi 331 gears for 600.00 was wondering what to check for to see if its worth buying
Thanks
Thanks
12 bolt posi what to check for
roudy
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G
Guest
·I think I read where any 12-bolt is worth buying at that price as long as it isn't out of a Truck...
pdq67
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pdq67
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And it's not an Olds 12 bolt copy.
Type O is the one to avoid- type C is Chevy:
![Image]()
The casting numbers/rear codes are listed by year on Dale's site.
Type O is the one to avoid- type C is Chevy:
The casting numbers/rear codes are listed by year on Dale's site.
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94 Posts
Not trying to hi-jack the thread... but, Mike, what is so different about the different types that you say to avoid the Olds? I have been trying to find out the differences to narrow down what I need for my Chevelle. Chevy 12 bolts are getting scarce and expensive. I have found the BOP have bolt in axles vs C-clips.
G
Guest
·I think the Olds's have 10-bolt guts in them is why. Even w/ the 12-bolt cover.
pdq67
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pdq67
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Eric ,the O-type Olds rear is what Paul said.
I say avoid as some think it's another 12 bolt Chevy (8.875") rear.
Has 12 bolt cover but 10 bolt internals -not Chevy type 10 bolt either.
Axles bolt in -has no c-clips (this part's good).
Parts are expensive and getting harder to find.
Gear selections not as good as 12 bolt Chevy 8.875 rear.
If you can use it and your OK with it , go for it.
I say avoid as some think it's another 12 bolt Chevy (8.875") rear.
Has 12 bolt cover but 10 bolt internals -not Chevy type 10 bolt either.
Axles bolt in -has no c-clips (this part's good).
Parts are expensive and getting harder to find.
Gear selections not as good as 12 bolt Chevy 8.875 rear.
If you can use it and your OK with it , go for it.
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1,503 Posts
The safest would be to make sure it has one of the following casting numbers that are only on Chevelle 12 bolt housings. See http://www.chevellestuff.com/qd/axlecodes.htm for more information.
Remove the cover to check condition of gears, etc..............
3859140N
3875745N
N3894939
NF3917124
3917124
3959038NF
3969278NF
3969278
1968-1972 in blue..........
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94 Posts
I had forgotten the guts inside on Olds 12 bolt were actually 10 bolt... that being the case, if you have an Olds 12 bolt can you pull out the insides and replace with a 12 bolt carrier, gears, and different axles? ( I heard the number of splines was less also. )
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12,343 Posts
Brian,
GET OFF OF THE KEYBOARD-------------------AND GO GET IT!!!!!!!!!
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12,343 Posts
Now let me make all of you cry.
About 8yrs ago, I stumbled across the 12bolt the is now in the 70 conv.
It was in a plain 69 Malibu in a salvage yard just down the road from the house. And it was EXACTLY what I wanted, 3.07 posi!!! Still in the car in EXCELLENT shape.
The guy at the salvage yard and myself pulled it, loaded it in my son's 66 pickup, I gave him $100 and drove off!
Got it home, tore it down, replaced 5 of the 6 bearings, installed new posi clutches (less than $200 for all parts), and then in May 08 just before CB08, I put in new Alloy axles for about $220 (Wally says Alloy has now closed their doors and gone home, what a shame!!!!).
Today, ANY rebuildable 12bolt core is at least worth $3-500, so a complete 12bolt is easily worth $6-800. :thumbsup:
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1,179 Posts
don't forget the 71-72 8.5 as an alternative. Not quite as heroic but almost as big.
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