Depends on the vehicle, but you did say "truck":
Fair sized chest toolbox behind driver's seat (all the usual stuff)
Wheel chock
Wildland fire gear
Gloves (several pair) and survey tape
Extra oil and brake fluid and rags
Misc ammo tucked away
Ice scraper
Spare tire mounted in bed
25' tow cable
12' and 4' chain with hooks
Hi-Lift jack
4-way lug wrench
Some baling twine
Axe, shovel, broom, cant hook
Stihl 046 24" bar in the grain drill toolbox
Gas/oil/tools for the saw + hard hat
I'm probably forgetting some stuff, but you get the idea. I could pretty much go contract timber falling again tomorrow.