Hahaha... OK. Too late.
Oh well, I can always sell it like I bought it.
That was my concern about buying one from eBay. Most of them are pulled from wrecked cars and only tested as far as pushing the buttons and seeing if it falls apart. This one was a rebuilt one that had been purchased from those rebuilding guys for $185.
I'm not gonna fry anything if I try it, am I?
I guess I'd rather not hose some future owner's ability to troubleshoot any potential problems. I'll wait for a w123 one to come up.