New to the duramax and allison tranny, but I have noticed that when I am driving about 60+ and push the pedal to the floor that the truck doesn't down shift it just usually slowly climbs speed. Is this normal? Truck is a 2005 2500hd crew cab with duramax, stock

It won't if your RPM's are too high and the downshift will hit close to the rev limiter. Try it at 55mph and see if it downshifts and how long it stays there.

At 60 you should feel the TC unlock, and a downshift, along with strong acceleration on up to 90 or so. At 75 you may not get the downshift, but you will still get strong acceleration - so it all depends on what you mean by "60+".


2004 2500HD LLY CC SB