im my 92 trans am, i know i have 3.23 gears. is it a 9 Bolt or a 10 bolt? i dont know to much about it, i jsut know the gear ratio. i was looking into upgrading to a Borg Warner 9 Bolt Series 3 Posi. i know someone who has one and i can get it cheep. it has a 3.45 gears in it. will this fit my car? can it be upgraded to 3.73 gears later? is this 9 bolt something that is a good buy? i dont know the kms on it or anything. anyone has expirence with these do tell me plz, i know nothing about rear ends other than gear ratios.

 

A 92 thirdgen will come with a 10-bolt. The 9-bolt was used in some 85-89 thirdgens. Yes you can use the 9-bolt, just dont forget to update the speedometer gears in the transmission to match your new ratio.
As far as upgrading, 9-bolt gears are more expensive and are getting harder to find. But it is the strongest stock rear end for our cars.

 

since it came on earlier third gens, would it have the same posi unit? would it be worth it to buy this and build up to hold about 500 hp? can you upgrade this to a 3.73?

 

You can't use a 9-bolt posi in a 10-bolt. - You can swap the completely rear-end no problems.

How to know whether its a 9 or 10 bolt? Lay on the ground, count the bolts in the cover......That said if for sure you have 3.23 gears, not 3.27, then you have a 10-bolt. And as Kevin said, a 92 would be a factory 10-bolt.

 

a 9 bolt will have a fill plug in the diff cover and the bottom of the main housing will have the borg warner insignia.
to tell what ratio it is , the ring gears are stamped on the outside edge so just roll it around and you will find it.

 

NOTHING is interchanageable between a 9-bolt & 10-bolt. And I mean everything.

 

I have a borg 9 bolt in my 91 interceptor z28, and it's a pain in the butt to try and find parts for, but on the good side the gear is actually a bigger ring gear and a little stronger than the 10 bolt, I put 390hp to the ground and haven't had a single problem with the 9 bolt