If wheeling is the destination, I pack everything I've got for spares. Everybody's kit will differ based on how hard you plan to beat the rig.
FJC
CV assembly x2
Tie rod inner/outer x2
Rear LCA/UCA
Unit bearing (pre-assembled) x2
Gear Oil/Motor oil
Rear drive shaft
Rear axle shaft (semifloat, wouldn't be a trail fix, but would have the part on hand)
Main toolbox (all drives/sockets-including axle nut, impact airgun)
Primary tool bag (wrenches, pliers, screwdrivers, etc.)
Secondary tool bag (punches, files, air fittings, grease gun)
Electrical toolbox (extra wire, relays, connectors and tools)
Hi-lift inside truck (disassembled, but out of the elements)
[edit] forgot that small red duffle holds small factory parts like shock mount bolts, pulleys, serp belt, and axle seals.
My tool kit lives in my truck, but I pack the spares for out of state trips. I built a platform for the rear cargo area and all of the above* fits below the platform and I pack gear on top of the platform.
*The bigger items like drive shaft and rear axles ride in the trailer. I'm working on building a spare 3rd member for events like Round Up, SCC or Mardi Krawl.
This picture shows most of my kit on the garage floor when I had to remove the entire rear cargo area panels to get to a errant weldnut for my roof rack a couple years ago.