What is the ratio
I would guess 3:42 but there is a label usually on the glove box door. It is called the Service parts label and tells the DNA of the truck. Take a picture of the label then do an internet search for GM codes, that will tell you exactly the axel ratio in the truck when it was built. I am attaching a picture of a Service parts label from a Buick car, so you will know what you are looking for.
