I carry all fluids, battery ends a very complete wiring kit so I can fix any wiring situation I come into, I also carry 2 .50 cal ammo cans packed full of bolts 1 is all metric and the other is all standard. I always have a t-case output shaft with me along with a spare input. I carry the old 21 splint coupler from my Mco7 for anyone else beings Ive upgraded to 23 spline. I carry spare belts, hoses a power steering pressure hose and a complete set of fron axles & birfs. I carry spare hubs as well. Hell I even carry spare brake pads too for some reason.
I try to be the guy out there that is always prepared for any situation at any time if at all possible. Ohyea I also carry a good first aid kit which is a must have.