I definately don't carry as many spares as Jon, but I am overboard on tools. Cordless makita 18v drill, 1/2" impact gun, portaband, sawzall, and angle grinder and 8 batteries. Sockets, wrenches, drill bits,taps, hilift, exhaust jack, welding rods, straps, chains and spare fluids. After grenading a th400 on slickrock, I realized I'd never have every possible spare. After swapping it out on the trail after finding one on craigslist and going to pick it up, I decieded the tools to fix anything are sufficient as long as you don't wheel alone. On the long remote trails, drivelines and axleshafts would be a good idea.