so im tryin to find out what gears i have in my truck stock it came 3.73 but i the 2nd owner but i got a buddy with the same truck with same gears n he can cruise at a higher speed on the high way than i can so im starting to think i have 4.11's? so my question is if it came with 3.73 would it have a good amount of clearance in the case or would they barely fit?? here is a pic of mine

 

divide your ring gear teeth by your pinion gear teeth that will give you your ratio.

 

Another way to figure it out is... spin the tires 1 rotation and count how many times the drive shaft spins and you have your gear ratio.

if the d-shaft spins 3 an 3/4 rotations then you hve the 3.73 and if it spins just over 4 times then you have 4.10s and so on.

 

Yes another good way if your pan is not off!!

 

yeah i did the turn the wheels thing already n it made 3 3/4 thanks man i jus toook of the cover to take a look n check a diff way

 

what size rubber do you run on and what does he run? This will affect RPM too.

 

yeah i run 17s he runs stock size 15's