I have a bed mounted tool box to keep most of this in ... but my "basic" list is, in no particular order:

tow straps, jumper cables, basic small tools (pliers, wrenches, screwdrivers), sig 9mm, folding lock-blade knife, climber's rope, duct tape, hard hat, boots, towels, spray paint, trailer hitch

All of that is always with me in my truck ... anything else that comes with me is "job specific" ... which is where the shovel, cinder block, and lawn chair would come in ...

 

I have an 87 f150 XLT lariat single cab long bed. I am looking for a toolbox. What size would I need or how do I find out?

 

If you mean over the rail toolboxes they make them in two sizes mainly, full size and small size trucks. Stay away from the plastic ones, they tend to warp from exposure.

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A hammer, the largest hammer you own. Even if it doesn't fix the problem, after using it, you'll feel better

 

First aid kit is handy if the nut behind the wheel springs a leak