I was desperate to find an xwhatsit converter but it looks like no one is making them anymore. I took a chance on this, and holy hell, it works! It even turns on the solenoid!
The drawback is that it has set the keys to a specific layout already and you can’t remap it the way you could we xwhatsit’s controller. But for people who can’t find a fully built out xwhatsit controller, this is a GREAT alternative, especially since it’s literally plug and play!
He said he also has a converter for basically most beamspring models (including the 6580 Displaywriter, which I’ve been looking for). I plan to follow up with him to see when he’ll post it on ebay