Here is the response I got from uAvionix...
Please check out the FAQ's for these products as they explain fitment and AML's
.https://uavionix.com/products/skybeacon/#faqs
https://uavionix.com/products/tailbeacon/#faqs
In there is this FAQ
Which aircraft have STCs for installation of skyBeacon?
Initially, there will be two STC’s for skyBeacon installation. The first STC is for the Cessna 172, followed by the Piper PA28. These high and low-wing installations satisfy the FAA requirements and will enable subsequent skyBeacon installations to be performed on any “suitable aircraft” without STC as a minor alteration.
A suitable aircraft supports the installation of the skyBeacon without airframe modification.
I don’t have a Cessna 172 or a Piper PA-28. How do I install skyBeacon?
The skyBeacon installation is considered a minor alteration and can be approved by the installer for most aircraft. At this time a form 337 should be completed and submitted along with the proper logbook entries. Please note, the installer must determine if the conditions are appropriate for installation on a specific aircraft. Additional guidance for ADS-B installation, performance verification, logbook entries and 337 instructions have been provided in the FAA policy memo titled “Installation Approval for ADS-B OUT Systems”