I am new to this site and a new dodge. . errr Cummins owner. I just bought a BDDL w/outlook and am pretty well satisfied with it and my truck also has the auto. I have been told that the new 48re trans in the 05 is pretty much bullet proof. I was told that the trans was designed to handle approx 800 hp and 1600 ftlbs of torque. I didnt hear that from and engineer however. I had an 02 duramax with auto and this 48re seems to handle the power better than the allison. I had a bully dog dynodominator in the duramax and it was way way fast. It was a Mustang gt eater (really bad too). This is my first dodge cummins and I have only had it a couple of weeks and only pulled 10k on a bumper trailer. It seemed to pull better midrange and top end than the duramax. The duramax was a 5 spd though. I have a really sttep hill that is about 3/4 mile long and has some turns that keep you from getting any speed so its mostly a slow pull no matter what kind of power you have. I would suggest if you are going to pull loads to change exhaust, air filter and get guages if you chip it though. I use Bully Dog and have sold some of them with no complaints whatsoever. I mostly used my duramax as a race car in disguise though. I will use the dodge for more work related activities. Sorry to ramble and I am sure there will be someone that has far more knowledge about the trans than me to read this post. I hope any of this helps.