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Thread: 2021 GMC 3500 AT4 Diesel standard bed SRW with 3.42 rear axle

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    2021 GMC 3500 AT4 Diesel standard bed SRW with 3.42 rear axle

    Does anyone tow with this truck?
    I am wondering about the axle ratio.
    How much will it effect towing capability?
    I will pull a 303rls. 12,000 lbs

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    Site Sponsor Canyonlight's Avatar
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    I don't recall anyone here with a 21 AT4 but there are a few 2020 Chevy and GMC 2500/3500 owners. Maybe one or more of these folks will chime in. I do recall that they all reported being very happy with the trucks/towing combination and very happy with the new 10 speed Allison among other things.

    You may want to do a search using 2020 or 2021 plus other key words like Chevrolet, Chevy, GMC, Duramax, etc. and see what comes us.

    Dan
    Dan & Carol
    2014 303RLS Reflection #185 (10/2013 build)
    2012 Silverado LTZ Crew Duramax 2500HD
    2700/16K Pullrite Superglide

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    Seasoned Camper
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    Your truck will laugh at pulling a 303RLS. I'm now driving a 2020 F350 with a gas 7.3 because I always felt my Ford 2018 6.7 wasn't even breathing hard to pull our 303RLS.
    2021 F150 Lariat Power Boost
    Sold - 2020 Ford F350 Tremor 7.3 4.30
    Sold - 2020 GD Reflection 303RLS

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    Quote Originally Posted by rrlowen View Post
    Does anyone tow with this truck?
    I am wondering about the axle ratio.
    How much will it effect towing capability?
    I will pull a 303rls. 12,000 lbs
    We have a 2020, but 2021 are the same platform.
    From what I saw all Duramax come with standard 3.42 and 10speed. The 3500 does come with larger axle components and gear ring which is supposed to be capable of putting down full torque in first gear (4.54 - 1st gear) while in tow mode. Supposedly lower ratio from past 3.73/4.1 6 speed is by design with newer 10 speed.
    Have not noticed any issues with towing and truck doesnt even seem to blink with our setup. Does downshift and hunt on initial downgrades as it will hold truck at speed a constant speed without any issue.
    I would have no issue with pulling a 303rls as ours is a 31mb, identical weight rating and just a few feet longer.
    2020 GMC 3500 Denali SRW SB Duramax 4x4
    2021 Reflection 31MB Goosebox 16k

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    Site Sponsor m&mjones's Avatar
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    Here's one link for you to review if you haven't come across it, there are other threads out there too. After unsuccessfully trying to work with GM and my dealer to get the factory setup installed and working on the trailer, I decided to go with an 8 sensor TireMinder system. A 4 sensor system (you can have up to 20 sensors synced with the monitor) would have been enough to use it for the trailer only, and along with the truck TMPS. I just like having all tires, including high temp alert, on one. I admit to occasional cross checking the TireMinder data with the truck display if I get bored.

    https://www.mygrandrv.com/forum/show...966#post315966
    Mike & Marta
    2020 Solitude 344GK
    2020 Silverado 3500HD CC standard bed Duramax/Allison
    Comfort Ride 184 hitch

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