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Thread: posi trac...

  1. #1
    Sr. Apprentice Evil_E's Avatar
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    Jan 2010
    Salty 'Ham Alabama

    Default posi trac...

    so what would you recomend? now correct me if im wrong, but my truck is 3.42 gears right? i dont race my truck or anything like that but would love to change it up a bit. now besides the gears im more interested in posi trac. so what would you recomend? i just figured if im messing with that might aswell step it up on the gears aswell. any insight is appreciated. 3.55s or 3.73s...pros, cons?

    K&N intake
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    Flowmaster true duals
    Viper 5900 alarm w/ remote start
    Pioneer AVICF90BT w/ nav
    Bell Tech w/ Nitro drop shocks

    ....and a bunch other stuff....

  2. #2

    Cool posi trac

    Theres not much differance between 3.42s and 3.55s. Id go with 3.73s, there a good compramize between economy and performance gears.

  3. #3


    now correct me if im wrong, but my truck is 3.42 gears right?
    There were a few different gear ratios installed in these, so it would be hard for any of us to simply tell you what gear ratio you have. Easiest way to find out (assuming you still have the factory installed gear ratio) is to look at your RPO code list in the glove box. Find any codes that start with G, then look those codes up on any of the available RPO code list databases (someone even posted one here once). While you're there, look for the G80 code, which is the RPO code for the factory "posi" that GM used in these trucks.

    If you do have an open differential in the rear and want to put something else in, it depends a lot on what you kind of "posi" you want: locker or limited slip. I see a lot of recommendations for an Eaton clutch type limited slip or Detroit's True-Trac geared limited slip for people (maybe like you?) who want something streetable but a little added traction under some conditions.

    2wd or 4wd? If 4wd and you decide to regear, recognize that you also need to regear the front.
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
    '92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
    "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World

  4. #4


    i had 3:42s in mine and went to 3:73s. didn't change the rpms too much on the freeway. i'm now turning about 2200 or so while doing 75. i'm wishing now that i would've went down to 4:11s because i didn't notice too much from the "seat of the pants" dyno. i also went with the detroit tru-trac unit and i couldn't be happier. my tires on the other hand, they could stand to be rotated lol

  5. #5


    Looks like a 2x i would say grab a rear out of 3:73 4x4 but i think you have five lug. might look into swapping you're five lug axle into that housing

    99 tahoe 2 dr. 4x4 7.4 4L80-e NP246, SAS, dana 60 hp, sterling 10.5 rear, gibson headers, and alot of tricks of the trade !!!!!!IF YOU'RE NOT CHEATING YOUR NOT TRYING!!!!!!!!

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