My wife bought me one of the fitted tool cases for my birthday a couple of years ago. Not real high quality tools, but a good variety of metric and fractional sockets, wrenches, allen keys, wire crimper, etc. It rides on the teansmisssion hump under the back seat of my extended cab Silverado. I have found these tools to be adequate for most small jobs. Also under the seat is a tire gage and a truck tire 12v
air compressor. It almost goes without saying that there is a roll of duct tape under there, also.
I carry a 4-way lug wrench in the bed of the truck. The 4-way is nice because you can get a lot of force without the danger of rounding off a tight lug nut like with an L-shaped wrench.
When we go on a longer trip, especially somewhere like west Texas where things are a lot further apart, I take a tool box in the bed of the truck with an assortment of bigger tools such as hammer, big crescent wrench, etc. and an assortment of small stuff like bolts, nuts, screws, tie-wraps, and electrical crimps.
I don't carry belts and the like except for Mexico.