Do I have 4.10 gears ?
 

The owner I bought it from said so..... It shifts out of first at like 35-37 mph and my old XJ shifted at 40-42 mph ? But I'm just not sure.... :cursing:

235/75R15
Cruising at 60 mph- 2000 rpm
Cruising at 70 mph- 2250 rpm

Oh yeah these are different H/T on my XJ now, got 4 new with 60k mile warranty for $150 installed and balanced.

www.grimmjeeper.com
Check out the gear ratio calculator

Ok it's in between 3.55 and 4.10, so I have 3.73 ?

you can find out for sure by taking your diff cover off, I'm sure they could use some fresh oil anyway.

Stamped on the outward facing side of the ring gear will be some info including the ratio.

Another way would be lift your tires off the ground and either in neutral (if you can rotate your drive shaft in neutral) or disconnect the driveshaft.

Mark the top of the tire and the top of the pinion flange (part sticking out of the diff connecting to the driveshaft). Rotate the tire one full rotation and count how many rotations you get at the flange.

That is your ratio. So mine would turn just over 4 times and be a 4.10. If yours are 3.73 it should turn 3 full and one 3/4 for one rotation of the tire.