Like anyone who is both rebuilding and building a project, the end result will also have some leftovers. Like the Johnny Cash song, "One piece at a time", some of the parts you buy are lost forever in the garage, some flat-out don't fit, some ideas died after some of the parts were purchased, and other parts were bought for a totally un-remembered project. That's life.
Somehow, I wound up with enough oxygen masks to outfit a senior citizen's center - I only wanted a couple. Somehow, the one oxygen regulator I was looking for turned into four (maybe they're like rabbits?). Even though when I retired from 3M, I was sure I had plenty of crimp-on terminals, I've found that the copy paper box full of 3M terminals was just a starting point. I also have a fire truck's exterior radio box that I bought for "something". I have friends in the 2-way radio service that have handed me radios that can probably contact Mars if the winds are right. I have a peculiar assortment of emergency warning lights in a variety of colors courtesy of some emergency vehicle electrician friends (and the only color I can use is amber...). The same folks have handed me 3-4 sirens (again, not very usable on an RV).
I've gone from buying LED lights, to considering becoming a dealer.
That's the way of the vehicle collector's world - when the buggy is finished, it will have some spares still sitting on the shelf (spares that aren't quite right, or don't fit, or don't do what I wanted them to do). And that's when I start showing up at flea markets as a seller....
And that's life.