gears in 86 xj

I am trying to determine why gears I have in my 86 xj , it has a 2.8 v6 with 5 speed. I have pulled the tag off the rear diff and the numbers are as follows ;

1 605293-3D
3003695

Those aren't the right numbers. There *should* be more numbers on there. But,none the less,you probably have 3.73 gears in them. If not,they *could* be 4.10. If the rear axle is open,chock the front tires and jack up one rear tire. Put the transmission in neutral. Now,mark one of the driveshaft's yoke ears with a white marker (makes it easier to see under there). Rotate the lifted wheel TWO COMPLETE revolutions (no more,no less) and count the driveshaft revolutions.

3 revs--3.07's-uke:
3 1/2 revs--3.55's -not bad
3 3/4 revs--3.73's-now we're getting somewhere!
4 revs--4.10's-:yelclap:

Hope this helps you out! :thumbup: