raceking46 Posted July 8, 2010 Share Posted July 8, 2010 My 70 monte has a non posi 10 bolt and I'm looking to get a posi unit for it but not sure if its 7.5 or 8.5 it appears to be the original rear axle. I'm sure you guys know what came in these cars or can atleast tell me what I'm looking for. lol I want to run 3.73 or 4.10 gears haven't decided yet. Quote Link to comment Share on other sites More sharing options...
Monte7071 Posted July 8, 2010 Share Posted July 8, 2010 Its not a 7.5 those are in G body,s. It could be a 8.2 or 8.5 you need to measure to be sure. I could swear my last Monte had a 8.5 by everything I read and when we opened it up it was a 8.2. Dont go by what was offered that year as over the years cars end up getting parts replaced. Quote Link to comment Share on other sites More sharing options...
bobsmc Posted July 9, 2010 Share Posted July 9, 2010 i heard there is a difference in the pinion nut size that can help with id on a 10 bolt. im sure if you do a search you came find out more. its something like 1"1/16th for the 8.2 and 1"1/4 for the 8.5 but dont quote me on that. bob Quote Link to comment Share on other sites More sharing options...
raceking46 Posted July 9, 2010 Author Share Posted July 9, 2010 Oh great this sounds like its gonna be fun. $$$pit Quote Link to comment Share on other sites More sharing options...
raceking46 Posted July 9, 2010 Author Share Posted July 9, 2010 I found the answer on the team camaro forums. Apparently the pumpkin casting for all 8.5s have two squareish/triangular nubs that stick out at about 5 and 7 oclock along with 4 humps around where the axle tubes are pressed in on both sides that the 8.2s do not have. Also they say that if the yolk has U bolts to hold the drive shaft instead of bolts and straps that its not an 8.5 Hopefully this info helps anyone else who needs to know. 8.2s apparently where common from 1965-1970 and unfortunately thats what I got. So now I gotta find a posi unit and good gears. Quote Link to comment Share on other sites More sharing options...
Chevyss Posted July 10, 2010 Share Posted July 10, 2010 That's good information to have. Hope all works out. Quote Link to comment Share on other sites More sharing options...
bobsmc Posted July 10, 2010 Share Posted July 10, 2010 i have a bop 12 bolt posi with 308 gears that i would sell pm me bob Quote Link to comment Share on other sites More sharing options...
Hobbes Posted July 10, 2010 Share Posted July 10, 2010 Hello to all dealing with questions and doubts about differentials! If you are ever in doubt, contact Jim Mitschke: J D Race & Restoration Muscle Car Differential Specialists Richfield, Oh 44286 330 990 8155 He also owns a First Gen Monte SS (forgot the exact year) and he knows a hell lot about diffs. In fact that is also his business. He is polite and very very helpful. He was the one pointing me also in the right direction to find out that my Monte has a BOP axle and diff even originally installed in the factory and documentated in the buildsheet due to the strikes in that year. If you are looking for BOP posi and parts you will realize it is a demoralizing way in respect to prices and availability. Jim can give you advice in the pros and cons of sticking to BOP or changing to a Chevy axle. Good luck to you raceking46! I have lying in my garage all the pieces for changing gears and posi over a year now. My next quest is now to find a trustful guy here in Hamburg (Germany) to help me installing it right Janin Quote Link to comment Share on other sites More sharing options...
7tonemonte Posted July 10, 2010 Share Posted July 10, 2010 Jim is on the boards here as well, Monzaz is his screenname,but he hasnt been around in a while Quote Link to comment Share on other sites More sharing options...
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