I followed FAA guidance and installed a Stratus transponder with its associated GPS antenna in accordance with the STC. The STC only has a few models in it not including the Pawnee. I filled out the 337 per FAA guidance and sent it off to OK City. It wasn’t a field approval but was a Major Alteration so no need to send it to the local FSDO. Again per FAA guidance. I don’t expect to get the 337 back. I expect it to just be filed with the aircrafts records as usual.

To reiterate there is no such thing as a “notification” 337..

I haven’t been asked to or researched putting an ADS-B out transponder into a glider so I can’t really speak to that. When I install the PowerFLARM brick into my glider in the fall I’ll get the ADSB out option and do the appropriate research/ paperwork.