Hi Chuck - I saw your post about a second GPS source in the panel. I had purchased a used UPS/Garmin SL-50 for just that purpose in 26J but now I've pivoted to installing a GNX-375 and keeping my GX-60 as a second com/gps. So I am planning to move the SL-50 along to someone that had the same idea I did.
So I don't know if you could use something like the SL-50 (non-waas), but I really liked it as a 1" GPS solution. I have it, the antenna, the tray, and the database update kit (think it's about 2-3 years old) and I've been planning to list it for sale but hadn't done so yet. So if you'd have any interest in something like that let me know. Pretty reasonably priced.
Some info on the SL-50 here: