Need help identifying 99 suburban front differential

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Johndavidrichards, Nov 14, 2011.

  1. Johndavidrichards

    Johndavidrichards New Member

    IMG_0168.jpg IMG_0170.jpg IMG_0794.jpg
    The picture on left is the one the salvage yard says is supposed to be in my truck according to build code. The middle picture is of the front Diff I just removed. The one on the right has both picture with arrows pointing to the differences.

    Build code says GT4 which is 373 ratio. Got used one from salvage yard and they claim it should match my build code however it is different. My unit only has one plug for the motor that switches the front diff but the replacement one has 2 plugs. One to a motor housing and the other to something that looks like a sensor. Of some sort. Any help in identifying would be appreciated. They are definately different.
    Last edited: Nov 14, 2011
  2. Johndavidrichards

    Johndavidrichards New Member

    Help a brother out. Anyone?


    Can anyone help
  3. ippielb

    ippielb Epic Member 5+ Years ROTM Winner 1000 Posts

    One out of your truck is a 8.25" IFS front differential. I just rebuilt mine out of my 2002 silverado, has exact same connection. You can screw off the plastic actuator on the one on your truck. I would stick with one that is from your truck. What is wrong with yours?
  4. Johndavidrichards

    Johndavidrichards New Member

    Thank you so much for the reply.

    My front diff is making a low grinding noise. Not real bad but you can hear it while slowing down from 50 mph and less.

    I'm planning a 700 mile trip each way back to Maryland and wanted to fix it before I left.

    If I can tell the salvage yard what I need I'm sure they can get it for me. I was just trying to confirm the following I guess:

    1. Is the one removed from my suburban the original front diff or was it swapped before I bought it to a newer one.

    2. Is the salvage yard wrong and what they gave me is not intended for a 1999 suburban?

    3. Assuming both above are correct then maybe I need to ask for a front differential for a later model silver?

    4. Rebuilding an option. I have a guy that can help me crack my old case open and see if it's just som bearings that we can replace.

    I really need to find a 1999 suburban in a parking lot and craw under for a look at someone elses.

    The question is do all 1999 k1500 suburbans have a front diff with one plug or do they have 2 plugs.

  5. ippielb

    ippielb Epic Member 5+ Years ROTM Winner 1000 Posts

    My replies in RED.

    Here's my differential from my 2002 silverado

    In all reality, this is what could be causing a humming or grinding, or if your gears are not set up properly, one of the locking tabs could have broken and set the backlash off and set the pattern crazy.

    I also had a bad bearing or two. Be sure to get your fluids changed!

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