The trucks I've had I always tried to keep a little bit of everything. various fittings up to 2" for flex rigid and emt. A "Baskin Robbins" assortment of breakers and fuses. Bushings, lugs, split bolts, tape, 3M mastic pads, "boy butter" pipe, paint, caution tape, electricians hand book, NEC, wire, sta-con terminals, wirenuts, screw kits, length of chain, assorted bell boxes and covers, numerous devices and a lot of other stuff I don't remember until I need it. And I don't even do much service work! Sounds like a bunch of crap but it all fits neatly if you organize it right and has had me come out like a hero more than once!