12 bolt car vs. truck

[mwilliams5891]

Ok it's been a really long time since I've been on here....but it's good to be back!!! Anyway I am back working in my C10 and I was getting the parts lined up for the rearend and was reading about the difference in car vs. truck and I don't know what I have....it was given to me not with a rig so I'm worried and I don't quiet understand what is different....is the housing? Or the internals? Or all of it? I was going to replace everything but the housing pretty much....new 5 lug axels and an rayon posi unit with new gears....but I'm scared of buying missmatched parts...I have tried to search on here and the Internet with bono luck so hopefully I didn't miss a lot...but anyway thank for your help!!! You guys are the best if the best
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[Ziegelsteinfaust]

Nothing interchanges expect maybe a few gaskets, and their gear ratio's are a bit limited by comparison.

They are two different rear ends, and the car is better in nearly every way. If I am not mistaken the 8.5 10 bolt is stronger in more ways too then the truck 12 bolt.

[Gumby]

Most of the BOP ones are nice for a shell because its 4 link ready, first thing you do to a race car and off road truck, 4 link system. on the cars it just wasn't adjustable with stock arms.

just be careful for the 8.75 10 bolt cover with a 12bolt carrier inside, lots of those are posi [got one] but no one makes parts and no parts from others will fit. [you can reuilb the posi] can't even get the right 10bolt cover gasket, as its bigger then a 10bolt, but strong as a tank.

[clinebarger]

1. Chevy car 12 bolt.
2. Truck 12 bolt.

[clinebarger]

Originally Posted by Ziegelsteinfaust

Nothing interchanges expect maybe a few gaskets, and their gear ratio's are a bit limited by comparison.

They are two different rear ends, and the car is better in nearly every way. If I am not mistaken the 8.5 10 bolt is stronger in more ways too then the truck 12 bolt.

The only things that make's the 8.5" & the Car 12-bolt stronger is the larger pinion stem diameter & only seen one break.

[Ziegelsteinfaust]

I've heard the axles are slightly better, and usually have more teeth. Also the main caps are supposed to be a touch better.

If my truck had one I wouldn't rip it out, and I would actually build it up a bit. There fine for just about anything thrown at them. Except 500+ HP, and sticky tires. Or heavy off-roading.

[Captainfab]

The 12 bolt car and truck both use 30 spline axles. The 12 bolt car gears can actually be used in the truck housing. There is a thread on this forum in the "Racing and High Performance" section with the bearing number to make it work.

There are actually a few members here that race their trucks and are still running the truck 12 bolt.

[mwilliams5891]

So how do I know what I have? I am assuming the housing are different...so do they measure out different? I'm fine running a truck 12 bolt I just wanna make sure I get the right parts
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[clinebarger]

Originally Posted by mwilliams5891

So how do I know what I have? I am assuming the housing are different...so do they measure out different? I'm fine running a truck 12 bolt I just wanna make sure I get the right parts
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The rear covers are shaped different....Did you not see my earlier post?

[Captainfab]

Here is a link to a page with some more info on identifying a car 12 bolt from a truck 12 bolt.

http://www.drivetrainshop.com/GM_12_Bolt_s/105.htm

[oldblue1968chevy]

I sold the rearend from my 68 to a guy with a chevelle who was tickled to get it? lol idk

[69trk]

I'm running a truck 12 bolt with moser 33 spline axles c-clip eliminators and a car 12 bolt billet yoke and a full spool with welded axle tubes.. Works great so far.

[mwilliams5891]

Originally Posted by clinebarger

The rear covers are shaped different....Did you not see my earlier post?

No I'm sorry It didn't come through thank you!!!! That was exactly what I needed!!!
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[JMac11]

Raced a Narrowed 12 bolt with factory posi for years, twisted an axle once, but that was about it. 3500# car 14x32 slicks running 10's It's all in setting them up properly.

[GASoline71]

Like mentioned earlier... the "weak" link in a truck 12-bolt is the smaller pinion diameter as compared to the car 12-bolt. But I have seen a lot of cats with trucks with truck 12-bolts putting some serious punishment to them, and they hold up fine.

Gary

[mwilliams5891]

Thank you guys just one last question and I know it's kind of broad but any idea what someone would charge to install the new posi axels exit if I bought parts....just strictly labor I have read the sticky and I might do it myself but just checking
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