In addition to all of the other items listed, I always like to have hard liquor and a large caliber hand gun at my disposal in the event of any "true" emergency
Seriously, the biggest issue is storage. I carry a rocket box on top when I am on the road and have a ton of room for everything - including a 5 ton floor jack and an air compressor.
Daaammmnnn, how do you wrestle that floor jack up there? Can't be fun...
While I may not always carry a large caliber handgun in the truck, I do sport all of my spare fuses and bulbs in a nice plastic Glock 21 factory case (not the newer clamshell cases, but the old style with the Tupperware lid, fits perfectly in the door side pocket).
