this could be an endless post <img src="/forums/images/graemlins/lol.gif" alt="" />

the short version:

for the welder:

get a welders coat - suede - for protecting yourself if you are under the truck
good welding helmet
leather gloves - always wear them
anti-spatter dip for tip of gun.
extra tank (or 2) of gas ( if it's a MIG )

other nice to have's:

Milkaukee 14" chop saw
Milkaukee 9" grinder
Milkaukee 4" grinder (or 2)
BIG vise
BIG bench grinder
Floorstanding drill press w/ 1" chuck
7" circular swaw w/ metal bladed (must have a metal guard on the blade <img src="/forums/images/graemlins/wink.gif" alt="" />)

if you want to work w/ tube:
tubing notcher
tubing bender

maybe some folding steel saw horses that you can clamp your ground to to mahe a potable welding table.