To replace or not replace

Discussion in 'Differential & Driveline' started by 88Squarebdy1ton, Nov 5, 2018.

  1. 88Squarebdy1ton

    88Squarebdy1ton Junior Member

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    Joined:
    Jun 6, 2016
    Location:
    Texas
    First Name:
    Glenn
    Truck Year:
    1988
    Truck Model:
    R30
    Engine Size:
    6.0L w/ 6L80
    So I have a '88 R30 (1 ton crew cab dually). Think original camper/RV tow vehicle. Came with a 454, Turbo 400 and 4:56 rear end. Could pull a house down but was slow at top end and used a LOT of gas so last year replaced engine and transmission with a 6.2L w/ 6L80 out of a 2015 Escalade. Runs great, cruises 70-80 mph easily (not towing), but still generate about 2700 +/- rpm for that speed. Someone has suggested a higher rear gear ratio, but I'm on the fence. They think I should be able to cruise at 75 w/ about 2000 rpm (and resulting better mpg).
    I am not yet, but plan to pull a loaded 3 horse trailer w/living quarters or a 5th wheel RV in the future and want to make sure I'm not struggling on the low end. Any thoughts?
     
  2. bucket

    bucket Super Moderator Staff Member

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    Usually not in Ohio
    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    Pulling and good MPG don't go together. Imho, leave the gearing alone if you are going to pull.
     
    Snoots and CSFJ like this.
  3. 88Squarebdy1ton

    88Squarebdy1ton Junior Member

    Posts:
    5
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    3
    Joined:
    Jun 6, 2016
    Location:
    Texas
    First Name:
    Glenn
    Truck Year:
    1988
    Truck Model:
    R30
    Engine Size:
    6.0L w/ 6L80
    Thanks for your reply. I agree and not really concerned about the mpg so much, it's certainly better than it was. I just am not certain that running 2600-2700 rpms consistently are too much for engine life either.
     

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