How to determine gear ratio?

[Glamping]

So I need to determine what ratio my truck has. Other than pulling the cover shouldn't one of he letters in the vin tell me? Thanks for any help

 

[webb06]

Should be a metal tag on the rear differential cover. It'll be under one of the bolts. It'll tell you if it's there

 

[Mark Kovalsky]

There is a data tag in the driver's door opening. There is a code for AXLE that will tell the ratio that it was built with.

You can also jack up the rear wheels, put the trans in N and rotate the tires one revolution. Have a helper rotate the other side while you do one side. Count the driveshaft rotations and you'll know the ratio.