The explorer 31 spline is 1" narrower than the factory cherokee axle.The ranger 28 spline axle was typicaly narrower than that depending on year(4" narrower 90-92 and 2" narrower 93-09) So just swapping the axles and spider gears will not work. And the Axle tubes are smaller in dia too. If your axle tube is 3.25" dia and necks down at the brake you have 31 spline, if it is 2.80" and does not neck down, you have 28 spline.
"Wheel it, Break it, Build it better." Words to live by.