I just did the Rubicon Trail (with my cousin in his TJ). There were 7 TJs in the group, 1 YJ and 1 XJ. From that experience, I am trying to make a list of pertinent tools, spare parts and a supply of bolts/nuts/misc to have along for the XJ on a trip like that where there is no cell phone signal, rough trail and a long ways from a parts store ... without adding more weight and bulk than necessary.

We did have some breakage on the trail (tie rod on the XJ, sheared a bolt in the steering of a TJ and a bolt came loose and lost in a TJ suspension set up). We also had a flat tire (was fixed with a plug).

Help me start a list of what to take along for tools and parts.

Ujoints, axleshafts,baling wire and duct tape.

I carry a tool box, both front axle shafts with the hub assembly on them already, tie rods, trackbar,front and a rear driveshaft a few sets of straps and bolts for driveshafts, I need to get ujoints next.I have a c8.25 but if you have a 35 I would carry rear shafts two.

I have a box of tools, enough to take apart the entire jeep (minus the torx) (don't forget spark plugs).
spare axle shafts
ujoints for axles and for the drive shafts
ball joint press ( to change out u joints because it's easier than using a hammer)
fuel
water
compressor
camping stuff
extra fluids (diff, oil, tcase)

Toilet paper, because you never know where Mother Nature is going to strike.

A CB can help hail others that are out there. Got a metric and standerd craftsman ratcheting dogbone. They dont fit everywhere but they are a lot lighter than a full ratchet set. A shovel has helped my buddies a few times.
Duck tape for sure. Broke my track bar in half and rode home with it taped up. Now i did have almost an entire roll of the stuff on there