Might go for an 06, I just read that the allison is getting a 6th gear. double overdrive. If I had the $ that's the truck I'd have. My father has a hd2500 8.1, allison, crew/shortbox. It's great to drive. Pulls like crazy, but only gets 10 or less mpg. The diesel upgrade is looking pretty cheap now. Didn't seem like such a big difference in 01. He is thinking about selling and buying a duramax
I did break a front axle shaft about a year ago in it, but it was replaced under warr.
and onstar was nice, We were alone with no cell and a long way from service in the mountains of montana. We were able to drive it home though before the tow truck got there.