The Garmin SL40 VHF COMM Radio The Garmin SL40 Radio, Garmin SL40 COMM Radio, and Garmin SL40 VHF Radio terms describe the same general avionics family, while exact identification should remain connected with P/N 430-6040-203. The Garmin SL40 Aircraft Radio, Garmin SL40 Communication Radio, SL40