I would like to up my fuel mileage. Is there a kit available to convert to part time four wheel drive with lockouts?

I have a '96. The switch for my transfer case is 2wd, 4wd auto, and 4 lo. From what I've heard, and from my experience, there is no difference in mileage in 2wd vs 4auto unless you're seriously using the 4 auto for real 4 wheeling when the 4wd actually is put to use. 4auto on the road is just fine. I believe your truck has a 4hi setting, this would cause a noticeable decrease in fuel economy. To really improve economy, open element air filter (K&N filter charger), larger MAS, larger throttle body, headers, exhaust, and a good chip. If you can keep your foot of the gas, you'll notice a BIG gain in mileage. Good luck,