Differential ID

Discussion in 'Got gears?' started by Luxus, Aug 16, 2023.

  1. Luxus

    Luxus Gold Level Contributor

    I just want to confirm what rear end I got in my new 73 GS.


    Pretty sure this is a GM 8.5 but I want to confirm with the experts. I will be pulling the cover to inspect inside and I want to replace the gasket.

    On a side note, it's got a leak past the pinion nut which I intend to fix. Shop manual recommends a specific sealant to use, but any silicone that works with oils should work right?
  2. Brad Conley

    Brad Conley RIP Staff Member

    Yep, 8.5" rear and posi no less. Someone smarter than me will chime in with sealant info.
  3. monzaz

    monzaz Jim

    MAinly ALL the rears are 8.5 in the A bodys... They did have the 8.75 rear with a kind of same LOOKING cover as the one you have pictured but larger diameter example pictured (they considered it the HD version for the A body wagons and tow package cars etc. ) ...but the guts / ring gear is 12 bolt .
    This is the Corporate 8.5 very common and a good rear ...has many many optional parts to buy and find in scrap yards.
    IF yours is an original Buick rear it will have BOLT in axles 30" long and 28 spline

    Attached Files:

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