Hi guys I have a 72 442 with a 10bolt rear, I also have a 1970 type o rear with a good posi in it, Question is will the type o posi unit fit in the 10bolt rear already in the car. Thanks paul

 

As far as I understand, your oem rear is an 8.5 chev 10 bolt.
Different carrier.
The whole assembly would fit of course, except for the different pinion yoke/rear u-joint.

 

Your understanding is wrong. When did the Type O become a Chevy? Show me a Chevy that uses the Type O bolt in axles.


You can swap the entire Type O differential into your car knowing that you will need a new driveshaft or you can buy the correct posi carrier & gear set of your choice for your current 8.5" 10 bolt.

 

Why would you change out the 8.5 corporate rear for an O type? The 8.5 rear axle is superior to the O type and parts are readily available for the 8.5.
The O type only has 10 bolts holding the ring gear and only has a 12 bolt cover.

 

Some people are looking for a type o for correct restorations.




They are somewhat rare, and expensive to modify with little parts
availability as previously stated.
If it has gearing in it you like, use it as is. My o type has been reliable for the 17 years I've owned it.
Making a driveshaft for the o shouldn't be expensive.



If you need to change ratios sell the o type and put the money in the chev 10 bolt.

 

He has a 72 that never came with a 12 bolt type O rear axles. They came with 8.5 10 bolt corporate rear axles and were not just Chevy axles. You can't even buy a ring and pinion gear set for a 12 bolt O axle. That's why I asked why change the correct rear for an incorrect rear that's not as strong as the OEM axle.

 

Sell the Type O, rebuild your 8.5..

 

Just so we're all clear, the 1971-72 ten bolt is a "corporate" (as in "Chevy") 8.5 axle. Other than the use of bolt-in axles instead of C-clip axles, all parts of this axle interchange with other 8.5 Chevy axle parts. The Type O, despite also using ten bolts to hold an 8.5" ring gear (though the Type O uses different bolt sizes than the Chevy), shares NOTHING with the corporate axle. Other than brake backing plates, nothing interchanges.

 

The posi clutches and S spring will interchange, also, but yeah, they are really totally different rear ends.

 

I promise I will never substitute the word chevy for the word corporate again.

 

I'm looking to convert my o type to a posi 342 but can't find the parts if anyone can suggest where I can find them.

 

Good luck,unless something has changed,they are not making any gear sets new @ this time. You can buy a converted Phord 8.8 posi unit from some vendors. Used is going to be your best bet or you can look @ the 3.42 posi rear axle I have for sale in the parts for sale section.

 

I called supercars unlimited today. FYI they said they will have new gears for the o in May. 3:42 at least , No price yet but not cheap.

 

Good Luck with that. Ask 507OLDS how many dates he's been given.