For the gears, the only part that really applies is I6, 31" tires and the tranny. If auto, 4.10s will bring your highway RPM up a bit higher than stock but that's good because it puts the engine in a better powerband and helps propel all the extra weight more easily. If you have a stick, it's a little more debatable but 4.10s or
maybe 3.73 will be a good match for those tires.
Dana44s come up on the Sale section from time to time. They are supposedly in some 87-89 Cherokees, but realistically almost every one of them is from an 87 but even those are rare. If you are positive that the rear is a D35, options include the Ford 8.8 or even a 29-spline C8.25; the C8.25 is virtually a drop-in since they were in Cherokees for half the production run. The 8.8 is close, and you can get the bracketry required through M.O.R.E
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