How do I find what gears are in my truck. I have to options of 3.73,3.42.
The truck is a 97 1/2T with the 5.7L engine

Look at the glove box sticker for the RPO codes.
GT4 = 3.73
GU6 = 3.42

So GT4 is the 3.73 gears which allows me to tow 6500lbs?

So GT4 is the 3.73 gears which allows me to tow 6500lbs?

Your Owners Manual should have a section on towing capacity. It all has to do with the truck GVW rating, engine size and gear ratio installed.