According to the Installation Manual, the following indicators are compatible with main switchable VOR/ILS/GPS Indicator output (Connector P4001) for the Garmin GNS-430 and GNS-530 GPS/Nav/Comms. GI-102 (no longer available), Garmin GI-102A, GI-106 (no longer available), GI-106A, S-Tec ST-180 HSI, King KI-202, KI-206, KI-208A, KI-209A, KI-525A, KPI-552, KPI-552B, KPI-553, KPI-553A, KPI-553B, Collins 331A-3G HSI, 331A-9G HSI, 331A-6P HSI, Bendix IN-831A, Century NSD-360, NSD-360A , NSD-1000 HSI, Sperry/Honeywell RD-550A, 650 HSI. The following indicators are compatible as well but not mentioned in the installation manual: King KNI-520, Collins/STec IND-350, IND-350A, IND-351, IND-351A, 331H-3G Basically, a non-converter type indicator is required for the VOR/ILS/GPS Indicator interface to the GNS-430/530 Note: The following indicators may be interfaced to the secondary VOR/ILS output of the GNS-430/530 (Connector P4006). This output only provides VOR/ILS information on the indicator not