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Transfer Case Pump Upgrade Kit, 1998-2007 GM Trucks

31 Reviews
SKU: 10001


To open instructions click here.

Here is the best upgrade you can make to your GM transfer case(model 136, 146, 246, 261, 261HD, 263HD, 263XHD, 261XHD). Prevent the ever increasing problem of pump rub.

What is "pump rub"
The GM transfer cases use a gear pump inside the case that is driven off the mainshaft. The pump forces oil to the planetary as well as the drive sprocket sleeve. Because the pump is driven by the shaft, the housing of the pump must 'float' in the rear housing. There are 5 tabs around the housing that fit into spots in the rear housing to position the pump. Over time, the pump can start to wear on the rear housing. GM installed a spring steel clip in the housing intended to prevent wear but the clip can break and render useless

Being that the pump housing is aluminum and is a harder material then the magnesium rear housing, it can wear a hole in the rear housing and cause a very small leak. This leak is high enough in the case that it typically will not leak when vehicle is not moving and therefor not leaving any drops on the ground. Typically the condition is not found until there is transfer case damage from running the case out of fluid.

Avoid costly repairs to your transfer case by preventing this condition.

Full installation instructions are available right here on this site. Look under the Tech Information link on the home page for step by step directions.

With installation of this kit, you will have a LIMITED LIFETIME WARRANTY against pump rub. If your case ever wears a hole in the new rear housing with the upgrade installed. We will buy you a new transfer case.

Included in the kit:

    • Merchant Automotive billet transfer case pump housing
    • Transfer case adapter gasket at trans
    • RTV Silicone
    • Blue Threadlock
    • Merchant Automotive sticker
    If you already have a hole in your case, its recommended to install a new rear housing for a proper repair. Lifetime warranty will only apply to installations with a new rear housing.

    Check out our transfer case upgrade as featured on Truck U TV on Speed Channel


    Application table.
    1500, 1500HD, 2500, 2500HD, 3500
    NP246, NP261HD, NP263HD, NP261XHD, NP263XHD
    NP246, NP149
    1500, 2500
    NP246, NP261, NP263, NP263HD

    1500, 2500

    FAQ - Transfer Case Pump Upgrade Kit

    What do I do with the OEM anti rattle clip when installing this upgrade?

    You can discard the factory clip during installation of this kit. Its been designed to work with the clip removed.

    What other parts will I need to install this upgrade kit?

    We tried to make the kit all inclusive for a basic installation. This is taking into consideration of course that its being installed as preventative measures. If its being installed as part of a repair or after pump rub has occured, there is no real way to know the extent of the damage inside the case until it is torn down. Most times, as long as the case has not run out of fluid, it can usually be repaired with a new rear housing and seal and prevented from ever happening again using the upgrade kit. Regardless of the reason for installing this upgrade, you will need to refill the transfer case with oil. We recommend our Performance Transfer Case Oil for use in ALL transfer cases.


    The Ultimate Solution to a problem found in Chevy and GMC light duty trucks and utilities from 1998-2007
    2500HD 3500 Silverado Sierra 6.6L V8 Duramax diesel: 2001, 2002, 2003, 2004, 2005, 2006, 2007 early *

    Ratings & Reviews

    31 Reviews

    • 3 stars
    • 0 reviews
    • 2 stars
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    • 1 star
    • 0 reviews

    Rub Kit

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    Product is everything as advertised,came in a timely fashion, only thing I would add to the directions is to lube the pump plates before you reinstall with grease or transmission fluid.

    2006 K3500

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    Fits perfect. Easy install. 263XHDGM

    Awesome! Thank you Merchant

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    I do not understand why GM did not do a recall on this issue. Thank you so much for making this product. I did not want a hole in my T-Case!

    Great product

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    Heard from a friend about this fix. Easy do it yourself update. Instructions are step by step, can't mess it up. Glad I did this before I had any problems with my transfer case. Also great that Merchant Automotive does offer bearing and seal kits.

    Pump upgrade

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    Great part easy to install. Easy on the wallet

    Great Product

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    The parts and the video on how to install them were great i have put about 4000 km on since i installed the new pump. the machining and fit of all the parts were great thanks for all the help and the follow up to make sure every thing went well thanks again and i have recommended you to a lot of friends who have a lot of duramax trucks and chevy gas trucks thanks again