I think it should be noted that your choice of gear ratio should be determined based upon the primary use of your truck. I will concede that 4. 10 is definitely better in the mountains, that's common sense. But the question is, what % of your time are you towing heavy through the mountains? If it's over 50% of the time then get the 4. 10s, but if you're going to tow heavy less than half the time, get the 3. 73's. With an 8k brick behind me I can pull every grade I've encountered between MI and CA with no issues. With 13K I would have wished for 4. 10's in a few places, but realistically I'm not going to trade my truck in for one with 4. 10's since the other 90% of the time driving the truck back and forth to work it's saving me on this $3. 10/gal fuel. I've pulled 13k through the mountains and even though the 3. 73's make it work harder, I have never had a problem conquering any hill, and I don't think I put any truck-life affecting wear on my truck by doing so. So what if you have to slow down a little for one 10 minute section pulling a grade? Once I BOMB the engine and transmission, the 3. 73's will be sweet for everything I tow.