# 69 GTO 12 bolt



## liljohn442 (Sep 9, 2010)

I'm looking for a used 12 bolt rear end for my 69 GTO. I am looking through junkyards for one, but no luck. I was really wondering what cars are going to have a 12 bolt that is going to be at least sorta easy to intsall and what cars to look for. Gear ratio is irrelevant right now just trying to find one to fix. Any help would be appreciated.


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## 05GTO (Oct 6, 2004)

Look for a series 3 12 bolt from a Chevelle, series 3 will work with ring and pinion gears between 3.08:1 to 3.73:1, if you decide to go with 3.90:1 and lower you will need a series 4,


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## GTO JUDGE (May 14, 2005)

liljohn442 said:


> I'm looking for a used 12 bolt rear end for my 69 GTO. I am looking through junkyards for one, but no luck. I was really wondering what cars are going to have a 12 bolt that is going to be at least sorta easy to intsall and what cars to look for. Gear ratio is irrelevant right now just trying to find one to fix. Any help would be appreciated.


I just sold my Chevelle '69 12 bolt with 4:10's. Try> JD Race & Restoration in Richfield Ohio.... 330.990.8155. Jim is his name.... tell him Vic referred you. He's a chevy guy he can guide you.


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## jetstang (Nov 5, 2008)

It's a needle in a haystack thinking your going to find a usable 12 bolt in a junkyard, unless you are going to convert and narrow a truck rear. Not too many SS454s sitting in the junkyards. Swap meet, craigslist and the like are better choices. You could also get a 9 inch (corrected) lol.. for it if you are just looking for strength.


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## liljohn442 (Sep 9, 2010)

I believe you mean 9 inch, but yea I'm probably just gonna use a 10 bolt till I can find one. Its not like my cars is so powerful it needs a 12 bolt. I just kinda want one.


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## jetstang (Nov 5, 2008)

I used a 66 Chevelle 10 bolt in my 70. The 66/67 rears are 5/8" narrower then the 68 on rears, so bigger tires tuck in better than stock rears. So, a 66/7 Chevelle 12 bolt would be the ticket if you can find one. I meant 9", I was just stupid, lol.
Most GTO's came with 10 bolts and lived at the strip.


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## Too Many Projects (Nov 15, 2008)

All SS Chevelles came with a 12 bolt as standard equipment, regardless of hp for 66 thru 70. 71-72 depended on engine. There are still many around. I bought a 3:08 open from a 68 last year for $375. The 66-67 axles use a different shimming system for the carrier and they're hard to find parts for. I suggest staying with a 68 up.
Do a Car-Part.com--Used Auto Parts Market search to see where they are.


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## SWEETJUDGE (Nov 2, 2010)

if at all concerned with appearance a 12 bolt is incorrect in a 69. only an option in 70 standard on 455 cars... Pontiac wise. the olds 12 bolt will bolt in & a bigger bearing i believe.. the chevelle 12 bolts will also work.. the pontiac 10 bolt is fine.. if gonna abuse it get the Pontiac HD Nodular housing BIG N cast in the snout BUT THEY ARE PRICEY and 3.55 to 4.33s can be used....


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## KarLvr (Oct 28, 2010)

I have a 12 bolt that will need the carrier hole for the spider gear shaft repaired, otherwise good. 3.42s There is a little play and I changed to a 9 inch. It is a posi and the hole probably could be welded and bored. 12 bolt cover with 10 bolt ring gear. All other components are good.


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## Too Many Projects (Nov 15, 2008)

KarLvr said:


> I have a 12 bolt that will need the carrier hole for the spider gear shaft repaired, otherwise good. 3.42s There is a little play and I changed to a 9 inch. It is a posi and the hole probably could be welded and bored. 12 bolt cover with 10 bolt ring gear. All other components are good.


That is an Olds O type rear end that wasn't much good to begin with and is very expensive to repair. It's worth more as scrap weight.


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## BearGFR (Aug 25, 2008)

Things to consider: A well and carefully built 10-bolt will live behind a 'more or less' stock engine just fine, especially if it's coupled with an automatic, a "not insane" converter, etc. Significantly up the power, loosen up the drive train a little, improve suspension to plant the tires, and it won't take long before the 10 bolt will be challenged to survive for long. Then you'll be in 12-bolt / 9 inch Ford / Dana 60 territory. Consider this: if you plan to race your car at all, most sanctioning bodies will prohibit a 12 bolt unless it has also been converted to use a C-clip eliminator kit. Read the doc for most C-clip eliminator kits and they will say "not recommended for street use". Plus, as has already been mentioned, the only 'correct' rear for a 69 is the 10-bolt. So, if you 'need' something stronger you're already going to be 'incorrect', so why not go with something that you know will be strong enough and won't introduce any additional problems? That's why for my 69 I chose a new Moser 9" with their high-spline count alloy axles. No C-clip worries/hassles, plenty strong, and the added benefit is that if I want to have the option of relatively quick gearing changes, all I have to do is buy an additional center section with gears and diff already set up - no, it's not cheap, but it's an option you can only get with a 9".

In the end, you have to choose what makes the most sense for how you plan to use the car and your budget.

Bear


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## liljohn442 (Sep 9, 2010)

It seems as if I am going to stick with the 10-bolt for a little while so I was wondering what gears I should put in it I want something that can take highway pretty easy but still have some low end power.


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## Too Many Projects (Nov 15, 2008)

I have a set of 3.55's on a 67 posi carrier that I have decide I'm not going to use. I've never had it in an axle nor opened the case to inspect the clutchs. Just going on what the guy I bought it from said that it was good. Shoot me a PM if interested.
3.55 is about as deep as you want for a mostly street driven car to keep the rpm in a reasonable range. If you currently have 3.08 or less, you will notice a significant increase in acceleration....


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