Differential Identification 63 Cutlass/F85

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    The differential in my 63 Cutlass seems like it needs some servicing.
    It appears to me that I’m needing:
    -Rear wheel (axle)bearings, retainers, and seals.
    And possibly the differential/anti-slip guts:
    -Side Bearings/pre-load shims
    -Rear Pinion bearing/shim(s)
    -Front Pinion bearing/spacers/seal
    -Anti-Slip clutch pack.
    So that I can find and order the components, I’m trying to identify what differential this car has. I cant find any reference to its identity in the service manual or online.
    I’ve seen vague references to a “GMC 9.25”, but am not sure.
    I do know from the ID plate and stamp on the housing, that it is an Anti-Spin (C117) differential , with a 3.36 ratio, but I cannot locate any other code on the exterior housing or axle tubes.
    Any help with this would be greatly appreciated.



    I am not even close to an expert on these rear ends and never had the limited slip rear end. I do know that the parts are not that easy to find because it is a 3 year only rear end and not a popular one at that. Over the past year or so I have slowly been buying parts from eBay for mine. Most of the bearings and seals are available on eBay but anything for the limited slip is not going to be easy. I am working 7 days a week and at least 11 hours a day right now so it would be a while till I can look up the numbers for the bearings I was buying from eBay. Hopefully someone else will have the numbers you are looking for or better information than I have at this time.


    I bought NOS rear axle bearings with retainers from Fusick about a year ago. PNs on the box are #391741 and GR.5.855. The box contained both the bearing and retainer. I think the axle seals are available new. I got a new pinion seal from either Fusick or Kanter Bro. Used my old o ring cover seal.

    What is the tag that denotes limited slip, got a picture? Didn’t know it was available on these diffs.


    Thanks for the info everyone. I’ll do some more digging for parts.
    See attached image for the “Limited Slip” stamp and tag location.
    The stamp is on the diff housing near the filler plug.
    The tag is basically a big washer for the filler plug. It could easily be lost if not careful.

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