I recently purchased a 2001 Chevrolet Silverado 2500HD Crew Cab Long Bed 4x4 with the Duramax and Allison. I was driving through town and I noticed all gauges lost power except the oil and volt gauges, and the truck was acting like it was in neutral. I coasted to a parking lot and shut it off and turn it back, still having the same symptoms(btw the whole time the engine ran normal). I called my local mechanic and he says it went into Limp Home Mode. After waiting 30 minutes I started it up and still the same, I was able to get it in gear and only stayed in first gear the whole way to the shop(because Limp Home Mode). He put the scanner on it and it was showing Transmission Communications Lost. Has this happen to anyone?