I have a smaller extended cab truck (s10) with jump seats that fold up ino the sides. In the center of the cab rear is the factory jack and lug wrench and I added a langth of pipe as an extension handle and a wrench roll. Behind the jump seat on the passenger side are nylpon straps and bungee cords for carrying loads, repair manuals and a soft sided day pack with more tools as well as some wd40, duct and electrical tape and a few small parts. Behind the drivers side jump seat I have the beginnings of my bob, another day pack with a couple mag lits and bulbs, a leatherman wave, dry granola bars. Also behind that seat are some gloves and bags of plactic silverware and condiments. So I'm kind of organized with truck stuff on the right and peope stuff on the left.
Also under the hood is a spare fan belt, spare spark plugs and wires, a small box with one of every bulb and fuse and a funner and rags for filling fluids. I have a box with extra fluids, but the cap from my old truck doesn;t fit the new one so I need to sell it and get a new cap then I can carry the spares box in the bed.