Bought 2002 HD truck 3 weeks ago, had it checked out at dealership before I bought it. The problem is when it shifts to 2nd or 3rd or 4th range when driving it normal, occasionally the engine does a brief rev-up during the shift. The shift is not sluggish. I believe it is mainly 3rd gear it does it in and only once in awhile. You can be driving around town and everything is shifting great and all of a sudden it throws this strange shift in. Anyone have any ideas? Do I need to get trans rescanned? I understand the 3rd clutches can have issues in this Allison but I can detect no slippage whatsoever. When you run it hard everthing shifts smooth and snug, its when the truck is run normal is how I drive this problem pops up. 109,000 mi, vin# 1GCHK23182F147678 This truck was driven to and from work, it has never pulled, next to perfect. Any Ideas?