Here's a few of the things I carry with me when I'm out.
Spare Axle Shafts (ujoints already installed on fronts)
All tools necessary to change said shafts
Fluids/gasket maker/brake cleaner
variety of tools
misc nuts/bolts etc...
containers to catch fluid
A must for all wheelers is Pig Pads or Petesorb (something to cleanup any fluids that might leaking in an emergency) of which I am currently out of. Hackle I need some more.
Small first aid kit (only sine i've known you Kat
Plenty of water for both human and radiator consumption
3 tow straps
funnels etc and other misc items that might or might not make in the trail box.
I have been constantly working on ugrading my trail box. However we never go out alone and usually someone has whatever someone else needs.