Ok 2 questions about OEM parts guys.
First I'd like to know if my stock ring and pinion will be at all sellable after I get them replaced. I'm making the jump to 4.88s and I'm wondering if I can sell my old gears (I think there 3.55s) or if that's just nonsense and nobody wants old used 3.55s.

Second, do you think u joints for an old 78 cherokee will fit in my Dana 30? They may not have been called xj's back in the day but they did have Dana 30s and I have 4 heavy duty u joints brand new still in the box from 78'

 

Go to napaonline, rockauto, etc. Look up u-joints for both vehicles and see if they're the same part numbers.

As for used gears, probably not much of a market for them.