well, like you mentioned these old trucks arent going to get good gas mileage to begin with but there are a few things you can do to help a little bit. for one thing, the biggest thing you can do if you're serious about getting better gas mileage is to get rid of those big ol' tires in favor of some others that are closer to stock size tires. also, make sure you air filter is a clean one. it does not have to be anything special but the main thing is that it is clean. also, make sure that you engine is running efficiently. your carb can make a huge difference in how much milage you get as well. are you running a race carb or more of a street application? then once you get the right carb on there you have to make sure that this is tuned correctly also. i'd say the biggest difference makers in MPG on these trucks are the tires you're running and the carb set up. i'm assuming yours is a 4x4 with those big tires so you cant really expect to get great as mileage to begin with but i'd start with these adjustments to begin with if you're serious about lowing your MPG.
