Why doesn't garmin have an email announcement list for this sort of thing?
http://www8.garmin.com/support/download_details.jsp?id=7129
Change History
Changes made from version 4.70 to 4.80:
Add AGL height data field
Add support for Bluetooth interface to Virb Ultra
Improve display of GDL 39 pressure altitude on datalink info page
Improve GEA 24 RPM signal processing
Improve support for pre-programmed supplemental map cards
Improve display of road labels on map
Improve GSU 73 software update process
General improvements to system operation
Includes update to GEA24 software version 2.80
Includes update to GSU 73 IGRF database version 1.03 (Base Year 2015)
Includes G5 software version 2.40
Includes GAD27 software version 2.20
Includes GAD29 software version 2.30
Includes GDL39 software version 4.70
Includes GI260 software version 2.70
Includes GMA245 audio software version 2.20
Includes GMA245 Bluetooth software version 2.00
Includes GMA245 software version 2.20
Includes GPS20A software version 2.20
Includes GSA28 software version 3.20
Includes GSU25 software version 3.60
Includes GSU73 software version 3.60
Includes GTR20/200 software version 2.80
http://www8.garmin.com/support/download_details.jsp?id=7129
Change History
Changes made from version 4.70 to 4.80:
Add AGL height data field
Add support for Bluetooth interface to Virb Ultra
Improve display of GDL 39 pressure altitude on datalink info page
Improve GEA 24 RPM signal processing
Improve support for pre-programmed supplemental map cards
Improve display of road labels on map
Improve GSU 73 software update process
General improvements to system operation
Includes update to GEA24 software version 2.80
Includes update to GSU 73 IGRF database version 1.03 (Base Year 2015)
Includes G5 software version 2.40
Includes GAD27 software version 2.20
Includes GAD29 software version 2.30
Includes GDL39 software version 4.70
Includes GI260 software version 2.70
Includes GMA245 audio software version 2.20
Includes GMA245 Bluetooth software version 2.00
Includes GMA245 software version 2.20
Includes GPS20A software version 2.20
Includes GSA28 software version 3.20
Includes GSU25 software version 3.60
Includes GSU73 software version 3.60
Includes GTR20/200 software version 2.80