I'd throw in a set of needlenose, jb weld (can help patch radiator in case of failure), superglue for those little things that rattle, I use the foot pump instead of T handle bicycle pump - much easier on an old man like me, tow strap, small floor jack, hammer, pry bar, spare bulbs/headlight, spare radiator hoses, diesel additive of choice and a container of hand cleaner.

If you're going through the mountains, sealed containers swell at high altitudes - they can gush fluids in unwanted places.

Codifex
1981 240D SkyBlue (needs an engine)
1983 300DTurbo w/sunroof