I got a rear end from a guy with a trak lock system on it. I wanted to swap it into my truck. My qeustion is, the guy said it was 3.73 gearing, but the little metal tag on the differential cover said 3.5, so I am wondering if it is a 3.55 gearing ratio and not 3.73. Is there a way to verify this since I have the entire gearing pack out of the rear end? Like counting teeth?

 

Count the teeth on the ring and pinion. Divide the ring number by the pinion number and youve got your ratio.

 

I think the only way to find out for sure is to count teeth or rotations.