Oooo! There is one item that I ALWAYS forget, and I know that mechanics have them/use them. It's a small mirror on a telescoping arm (about the size of a car antenna), used for spotting hidden leaks/dropped nuts/screws, etc. They're also dead useful for peeking around corners when you don't want to get your head vaporized.
So . . . we'll look for the aforementioned stuff, plus a few extra weapon power packs (if we don't have enough already), and that mirror thingy if I can find the equivalent of a Piston Ring or UAP/NAPA out here.