Diff gearing..
 

Does anyone know if gearing in dana 35, years '91 and '92 are same? I bought used '92 rear end and swapped for my bad '91. Will i need to change gears in it to match front or am i ok?

Should be a tag on the diff that says what ratio. I'd count just to be on the safe side. I think there are differences with manual/auto, and maybe 4/6cyl, there are different ratios so double check.

They are both stock 4.0 dana 35. Tags are different but i checked numbers on origanal rear end and they are slightly different from the factory, but new/ used 92' rear end does'nt have the big tag, just the two little ones, and original just had big tag and no little ones, but the little tags on newer one said 35 on one tag and 7 and a 6 on other tag, and big tag on original has a 7 and 06 on bottom row of numbers. ( u get all that? ) and ty for your time

correction...original front and rear diff numbers are slightly different on stock 91' xj i know both are original, i know the two previous owners never modified. First owner bought brand new. 4 wheel drive worked excelent until rear end started whining a bit and i decided to replace it. New one works great, just afraid to put it in 4 wheel drive until i know for sure gearing is compatible with front

The ratio will be stamped into the side of the ring gear. That will be the best way to check them.

Ok, so pull covers then i guess....

Thanx again for help

Gear oil is due to be changed every 30,000 miles anyway..............