The other thing to keep in mind is that if you don't know you have it, or you don't know where it is, it's worthless. I can't tell you how many times I go for my annual van cleaning and pull out all the stuff I didn't know I had, or the stuff I thought I had but never would have looked there.
Keep your truck clean, and once you use a part replace it right away. that way you can memorize your working stock and not have to wonder the codition of you device bin, or your plate bin. Nothing profound, but I find I need to remind myself of it all the time.
