There should be a tag on the rear diff or and I am not too sure of this, the numbers on the door post, some how that can be translated.
Good Chance it is a 28 spline unit.
Ranger FX4 LvL II’s had the 31 spline and the Explorers do along with the LS.
I found a tag on the rear diff cover, mine had a few letters and numbers, don’t remember what.