Register now to get rid of these ads!

Technical GM 8.75-- 10 Bolt differential

Discussion in 'Traditional Hot Rods' started by Thomas Schaar, Apr 27, 2017.

  1. PeggySue
    Joined: Sep 5, 2016
    Posts: 364

    PeggySue
    Member

    Decided to change differential oil , so I ordered a 8.2 differential gasket, only to find out it was to small. It was 9' center to center bolt holes, mine is 10' center. Anyway after researching I found out my differential is a 10 bolt 8.75. It has the 12 - 3/4" head bolts holding the ring gear to the carrier and 3" axle tubes. Only number marking I can find is on the back side of differential bottom, one side clock dial with hand on 2 and letter F, other side number 480632. I found they only made them in the early 70's for heavier duty applications , towing etc, parts are hard to find. Anyone know where one may find differential gasket , if not I will do the Permatex RV gasket maker.
     
  2. drptop70ss
    Joined: May 31, 2010
    Posts: 1,167

    drptop70ss
    Member
    from NY

    post a picture of the rear cover, never heard of that. 12 bolts holding the ring gear to the carrier means a 12 bolt rear. Only oddball I know of is the olds "12" bolt which is really a 10 bolt, 12 bolts on the cover and 10 bolts holding the ring gear to the carrier.
     
  3. saltflats
    Joined: Aug 14, 2007
    Posts: 10,545

    saltflats
    Member
    from Missouri

    Nothing wrong with RTV if use correctly
     
  4. PeggySue
    Joined: Sep 5, 2016
    Posts: 364

    PeggySue
    Member

    You can go on crankshaftcoalition.com , look under differential idenifcation Scoll down 2/3 it will detail the 8.75 10 bolt. That's what I found out they weren't made very long so not much about them
     

    Attached Files:


  5. PeggySue
    Joined: Sep 5, 2016
    Posts: 364

    PeggySue
    Member

    The picture of the gaskets is the wrong one, but the cover is the 8.75. If you go on the crankshaftcoalition site you can see the whole posting.
     
  6. mike bowling
    Joined: Jan 1, 2013
    Posts: 3,556

    mike bowling
    Member

    Check the "Summit" catalog too- they have pics to ID gaskets and ring gear diameters.
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 47,787

    squirrel
    Member

  8. dirtracer06
    Joined: Sep 29, 2009
    Posts: 198

    dirtracer06
    Member

    Opps. Carry on.
     
    Last edited: Apr 27, 2017
  9. What size brakes on the rear?

    I really like the right stuff gasket maker
     
    saltflats likes this.
  10. saltflats
    Joined: Aug 14, 2007
    Posts: 10,545

    saltflats
    Member
    from Missouri

    That right stuff is some bad a$$ stuff.
    I only like to use it for things I never want to take apart.
     
  11. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,599

    greybeard360
    Member

    10 bolt and 12 bolt.... Number of bolts on the cover. There is an early and a late.... Yours looks like the late one.

    Sent from my Moto G Play using The H.A.M.B. mobile app
     
  12. drptop70ss
    Joined: May 31, 2010
    Posts: 1,167

    drptop70ss
    Member
    from NY

    10 and 12 bolt refers to the number of bolts holding the ring gear to the carrier, not the cover bolts. An olds "12 bolt" with 12 bolts on the cover is not a true 12 bolt rear.
    I have seen that HD 10 bolt before, have had them in big wagons that I used to buy for the 400 small blocks. BOP style cover but would like to see someone measure that ring gear, they were 8.5s as far as I knew. Crankshaft coalition is just another internet database written by you and me, who knows what is fact.
     
    Last edited: Apr 27, 2017
  13. Not 8.5's. Not 8.75's either. They are 8.875 10 bolts. Heavy Duty..mostly station wagons.
    10 bolt cover, 10 LH 1/2 " bolts. 31 spline, not 28 ,like 8.5's
    Good luck finding it on the internet. The one Jim showed might be it.I can't remember.
    Probably need to go to a parts store that still has books. Good luck there too.
    Interesting to hear if this car has 5" b.c. axles.
     
  14. PeggySue
    Joined: Sep 5, 2016
    Posts: 364

    PeggySue
    Member

    Tried to order this one at Oreilly but the parts guy said he couldn't for who knows why.I found one same one(brand,part number) at CARiD.com, will know today, order coming. The differential in my 50 is a 1973 chevelle station wagon and it is a 10 bolt cover with 12 bolts holding the ring gear, 3/4" head, 3" axle tubes. It all fits with the description on crankshaftcoalition
     
  15. boltupal
    Joined: Dec 27, 2010
    Posts: 277

    boltupal
    Member
    from western ny

    That is a 8 7/8ths corp 12 bolt. Does it have bolt in or c clip axles . I think i have some parts for those. As far as gaskets go i just use black RTV. Finding gears and posi carriers very tough.
     
  16. PeggySue
    Joined: Sep 5, 2016
    Posts: 364

    PeggySue
    Member

    Posting picture
     

    Attached Files:

  17. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,964

    Truckedup
    Member

    Regular black RTV gasket maker works fine if you clean the surfaces well and let it cure overnight....I have done this on many rear axles with zero leaks for many years...
     
  18. PeggySue
    Joined: Sep 5, 2016
    Posts: 364

    PeggySue
    Member

    Picked up the red and ultra grey, yep had the black in my hand
     
  19. PeggySue
    Joined: Sep 5, 2016
    Posts: 364

    PeggySue
    Member

  20. Glad you found it anyway. You were correct on all counts. Very rare rear in Chevelles/Malibu's .
    More common in big wagons.
     
  21. For what it's worth, that axle cover gasket was first used in 1965, on full size Pontiacs. Thru 1970. Starting in 1971 thru 1976 it was referred to as P or M style axle. GM part number 9778192
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.