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Thread: Duramax and allison swap

  1. #1
    Tuner
    Join Date
    Jan 2016
    Location
    East Bend NC
    Posts
    117

    Duramax and allison swap

    I'm going nuts trying to calibrate my speedometer, so far the closest i can get is a 5 to 7 mph diff( speedometer to fast for actual). I keep changing or lowering the revs per mile but nothing seems to get it any closer and i'm a bit baffled as to why up to 55 on speed reader it's 5 to 7 mph fast but above that it's 12 to 13 mph fast what's the deal there?. This is a 2007 LBZ allison swap into a 1996 GMC sierra 2500. At first i was flashing the TCM but that did nothing so now i'm flashing ECM

  2. #2
    Tuner
    Join Date
    Jan 2016
    Location
    East Bend NC
    Posts
    117
    I figured it out,even though I verified I have 4.10's I changed the tune to 4.56 this morning and it's now dead on