I am a new user, and first want to say that overall I am happy with my 2001 2500hd Duramax and Allison. That being said, I had to replace the Allison at 44,000 because of continually going into fail safe when it shifted from 4th to 5th, but sometimes other gears also. My new problem is a little different, sometimes, but especially when towing, my truck will just loose power for several seconds, and after that it will again run fine, this happens in no particular gear, but more often when towing up a hill. Besides annoying, it is extremely dangerous, as most of the hills in San Diego County that we take to the desert are one lane. My trailer weighs between 10,000 and 11,000 depending on how loaded. I have been told injectors by other people (ATS transmissions), but since mine are not leaking the dealer can't find anything wrong. If I install a performance software such as hypertech, the truck is almost undriveable as it loses power very often, several times within 10 miles. I had the transmission built specifically for additional power, but I can't even use the power I now have. I have ATS's kit, converter, and trans-go, but my installer is having difficulty programming because of the loss of power. They also believe that it is some sort of fuel pressure loss, or fuel shutoff. I hope someone else has experienced this, and has a possible repair fix. Thank you