@Mike Goble replied to the recent “car broke down today” thread noting that he goes out to find fuel senders from E28s to have around. I found an old thread about the items that people keep in their car for roadside repairs, but what about the parts that are worth keeping an eye out for to have “on the shelf just in case”? Obviously if you’re @sfdon you have a huge stockpile because you’re constantly rebuilding cars, but for the newer owner like myself, any specific parts you guys with experience would say “snap that up if you see it, and don’t get rid of the one you replace on your car”. For me obvious ones might be things like relays - I’ve replaced my fuel pump relay and the ones in the engine bay since they look original and probably deserve to have a new one in position, but I suspect worth keeping the old ones rather than trashing.
when I owned a coupe) a new heater blower motor. Bought that from a mechanic on Long Island who was retiring. Less than a year later my motor went. And certainly, keep those old working parts that you replace. They still work.