I posted something in the other thread about manual shifting speeds. It seems to me that the issue is not at which speed the truck should be run at, but at what RPM your at whatever speed your going. For instance, driving 70 MPH at 4200 RPM's (what's that, 4th gear?) may mean that you can go equally fast up a 32% grade as you can across flat open farm land - because your torque curve is at its peak, all 280 foot pounds of it - and the resistance probably never exceeds that number (well maybe at 32%..). However that is total overkill and you'd be burning fuel just to keep the pistons pumping.

The same applies when you're at 900 RPM's in 6th gear going 30 MPH and your engine knocks every time you go drop below 28 and have to accelerate back to 30..

It would be cool if there was a resist-o-meter gauge in the Xterra gauge cluster. Basically it would work like a torque converter in an automatic, only it would be graphical and tell you when your resistance exceeded a certain torque limit where it cost more fuel at X gear than it was worth, or where the resistance was so far below the torque number that you were wasting RPM's.. Like two numbers, say - 220 resist, 214 torque - means you need to shift down.