OK that posted so we will try again.

Gears, tires, modifications. As near as I can tell the truck is bone stock except for aftermarket wheels with 265/75/16 tires. I crawled under it and could not find a tag on either differential but the engine is not spinning up enough to have a gear set in the 4's.

Driveability, I grew up in my dads repair shop and wrenched professionally for over 20 years and the truck has good throttle response, the engine is crisp and not laboring like something is wrong. I have not kept a detailed log of fuel usage however I used to have a second home in the mountains. It was a 230 mile round trip and if I went up and did not do much driving up there I would get home with slightly less than half a tank. If I put 30 to 40 miles on the truck up there I would need to stop for gas on the way home. My normal usage is Los Angeles traffic which if you know it no explanation is necessary if you don't no explanation is adequate. In that environment it will suck the tank dry and set the low fuel light in less than 200 miles, sometimes a lot less.

Tune, It had new plugs and filters in it when I bought it, I am assuming that they are the correct ones because I found it at a dealer and in 20,000 miles of driving the economy has not changed. On the subject of tune what about different plugs like E3's they make a lot of claims but what is reality? Also what about one of the aftermarket tuners? If the thing had a carburetor and distributor I would be playing with re-jetting and re-curving the distributor but it is not so easy with electronics. I never thought about the O2 sensor, cheap enough to throw one at it and see what happens.

Quadrasteer, I normally drive in 2WS because of an undiagnosed problem with the rear steering dropping out of 4WS into 2WS and not centering the rear steer. That is another thread.

Denali, my truck is the only non denali quadrasteer I have seen. Do not know if it was ordered that way or not but it seems to be a one of or close to it.