Spares I carry: half shaft, tie rods, u-joint (small, lightweight). I will sometimes carry Bigunit's spare steering rack but less inclined to do so now as the Scorpworks steering rack mount is working so well. Really, you need things that can break on the trail but are reasonable to carry. For example, a front diff or transfer case may fail but those aren't reasonable to carry. Other things might fail, like a driveshaft, but you can get off the trail without those items.
Besides spares, you need the specific tools to do those repairs: 35mm socket for the hub nut (and test fit it first as some sockets fit, others don't); 21 mm open end wrench for the inner tie rod nut; 21mm deep socket for tie rod end nut; 24 mm socket and box end wrench for the steering rack; tie rod puller or small sledge to loosen tie rod end and ball joints for tie rod and half shaft replacement; breaker bar and/or impact with a lot of torque; bungee cords to hold stuff out of your way during these repairs; deep socket for ball joint nuts (forget the size - 21mm or 22mm?); spare fluids: brake, power steering, engine oil, grease (which can be used in the diff, at least to get you off the trail), water.
