My 23ES uses a Garmin GPS 20A position source. Works great. I use a GDL 52 for ADS-B and SiriusXM "in" on the GDU. Awesome. However, I want to remove the GTX 23ES / GPS 20A and replace with a GTX 32 Mode C with a GDL 82 so I can get away from the non-private 1090ES system. But the 23ES works so well I can't justify the down time so I have to wait for a project to come up before I tear into it.
(a few more airplanes too)