The best thing to bring is a group of experienced wheelers/wrenchers with similiar vehicles as yours (Isuzus).

But regardless a basic list would include:
Spare tire, and items needed to change it.
3qts engine oil and filter.
tierod and tools to swap it.
belts(s)
maybe a spare hub or drive flange

Tools (probably a few things missing here)
8, 10, 12, 14, 17, 19, 22mm wrenches and socket (w/ratchet and extensions)
screwdrivers
wirestripper/cutter
couple types of pliers
2-3 lb hammer
misc wire, connectors and fuses
JB weld
Duct tape
WD-40 (or similiar)
funnel
TP

You don't need to bring every imaginable spare part and tool on the trail. It adds unneeded weight, and really there is a limited amount you can (or will) fix on the trail anyway. You need the tools for the parts and things you can easily fix. Or to rig something to get you off the trail so you can hitch a ride in to town for parts.

Generally with use, you'll get a feeling for what tends to fail on your vehicle and carry the parts and tools for the items that will leave you stranded. Like tierods or the poorly placed oil filter on my 98.

-Mike