I would do an inspection if in the truck or on the ground.

jack up/open diff cover/check axles u-joints at wheel hubs turn one opposite directions looking for slop/broken axles.

look for gear lube leaks around pinion seals/same for xfer seals.

look at all teeth on spiders/ring/pinion for sharpness/breakage/wear clearances.

like said wheel bearings are a high wear item, so just figure for new ones.

the housings/knuckles/spindles are the most important things to have as spare parts. these are hard to come by when worn or broken

did I mention how important a bearing spindle is? those small stub axles are gold as long as the threds are good..... FYI biggest problem is worn bearing and over torqueing the nut till it strips for running out of threds on stub axle.

so check nut and thred conditions

I always like to have spare parts to keep repair what was in my 79 RC over R&R the whole unit for repair (most times)

tie rod and dogbone are worth saveing if they are there.

I have only had 2 203 xfers wear enough for the chain to slip but they broke/busted not long after that thrashing it.

never any issues from the range box just chain slippage & breakage from chain.

IMHO you cant go wrong having any of it as a spare on hand. try finding it when your down and NEED to find it.