Welcome! Let's see how we can help ya out.

Like mentioned there were three axles offered.
(1) Dana 35 84-01 standard axle. They were non c-clip up until '90. Other wise pretty similar between years.
(2) Dana 44 87-89. Hard to find and usually expensive when you do but a great option none the less.
(3) Chrysler 8.25" 91-01. Plentiful and cheap as the majority seem to have gotten them and its not much of an upgrade for other vehicles so they're not plucked clean. They were 27 spline from 91-96 and got the stronger 29 spline in '97 till the XJ finished its run in '01. Built can handle 35s+, depending on build and driving habits. They do take up a bit more clearance than the 35 but worth it if you're planning on bigger tires.

The gear ratio can be found three ways without a tag on an axle you're looking to purchase.
(1) rotate the drive shaft (if in the vehicle) or yoke (if out of the vehicle) one full revolution nearly exact. While you do this count how many times the axleshaft turns. Markings will aid in this. I.e. 3.5 turns of the shaft to one turn of the yoke equals 3.55:1ratio.
(2) open up the diff cover and the ring gear should be marked of the ratio on the side face.
(3) count the ring gear teeth and divide it by the number of pinion gear teeth.

Since you have the Dana 35 you may also have abs. Swapping in a 44 or 8.25 will negate the necessity of deleting the abs operation.

If you do end up going with an axle other than the 35 try to obtain one from a model with the same transmission as yours and get the drive shaft as yours will not be the right length.

If you're doing the work, why not upgrade!

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