hey everyone, i just had a few ?'s about my truck. Lately, it has really been overheating,and gets pretty close to redline, i have to crank on the heater, and even then it doesnt lower too much. should i not drive it anywhere till i get it fixed, or will it be okay. also, i do a lot of highway driving, and not so much rock climbing(being from IL) and i was just wondering what anyone suggests to increase top end( 70 and i am at like 2 1/2 grand) adn gas mileage. is it going to be dealing with the gear ratio, or what are my options. it is a three speed with granny gear. just wondering what i could do. thanks for any help.