i have a 1993 gmc van 1 ton old school bus that i use to tow racecar and trailer. does anyone know how to tell what rear end is in bus and what gears i could switch to for better milage and easier towing? the sticker in glovebox is unreadable and can't find tag on diff.

 

The rear end that usually came in those a Corpoate 14 bolt rears. They came ina cariety of gears and configurations. Yours most likely is a 3.73 or 4.10. You can take the rear cover off and count the teeth of the ring and pinion. Divide the ring gear number by the pinion gear number. This will tell you what you have. Such as 41/8.