> I still haven’t figured out what to do with the old unit
I don't have a success percentage to offer you, but I've seen quite a lot of that kind of thing in the "free" section of Craigslist. There are all kinds of folks who grab that stuff for parts, for the challenge, or who knows
I've also seen mixed opinions about the best way to use that section: one audience thinks "put it on the curb, announce the fact you did so, the end" and the other audience is against that because it could cause multiple people to drive to what could be an empty curb by the time they get there. I'd say go with whichever causes you the least emotional stress: fielding bazillions of Craigslist emails or running the risk of inadvertent climate change contributions