Looking to have a unit built for a 73' C body. Since these posi rears are more rare than Bigfoot sightings we are looking to have one built. What's the general opinion 9" or 12 bolt? The bolt pattern on the wheel hub would have to be 5X5 to match the fronts and the wheels. I'm thinking 9" parts would be more easily obtained in the future if needed and not sure if I could get 5X5 axles for a 12 bolt. Brakes will be converted to disk. Also, wondering what other challenges we might not anticipate other than the portioning valve.

Side note: I see Deadeye has hit the 1000 mark, so I went back and looked at my number. I've hit the 911. To the general population this may be much of a mile stone but for a first responder it stands out.

 

Which rear end do you have in your car now? Would this one from a 1975 Riviera fit? This guy is located in Brooklyn.

https://www.ebay.com/itm/12-BOLT-GM-...QAAOSwFSNb81-p

 

Moser will drill any bolt pattern you want into the flanges.

 

The original from 73' but it needs a 9-3/8 which are very difficult to find. That's why having one built with readily available parts is the option we are looking at. Went down this road last year and after much homework and advisement found out the rears were made by Olds for the BOP's and only from 71' until 76' or 78'. Riveras had them which are a bolt in but he big cars only got them if you ordered that option. My thinking is even if you find one they are more expensive than building one and if something breaks you are back at square 1.

 

Here's a good thread with info on the 9.3 and 9 3/8 full-sized rear.

https://classicoldsmobile.com/forums...erchanges.html

Our member; Monzaz, is the go to guy for info on these hard to find parts. I've often wondered what I will do with my 71 98 if I ever get to the point of restoring/replacing the rear end?

 

Thank you