I agree if you're towing 99% of the time, get 4. 10's. However, I'd say most of the people who hav to ask would be better off with 3. 73. It was a tough decision for me, but I'm glad I went with 3. 73. So far I have towed my 8. 5x20 enclosed car hauler over the sierra (12307' of climbing) many times with zero problems. I just set the cruise at ~60 and stay between the lines! With the trailer empty it doesn't even come out of overdrive. Loaded (about 9-10k) it will go to 3rd locked on a few of the hills but always maintains speed. On one of the long steep hills where it normally downshifts loaded I can floor it, gain speed, and let it shift back up around 70-75... as long as there are no cops around and I don't mind paying $$$ for fuel! I'm sure if/when I add a box and get some power it won't even have to downshift loaded. At no time have I wished for the 4. 10's with the '05.