The upgrade of a GTX 335 to the GTX 345 is relatively easy, however is not a “plug-and-play” swap.

The GTX 345 includes integrated ADS-B In capability while the Garmin GTX 335 is ADS-B Out only. 

Both units share a similar form factor in the mounting rack and main connector but upgrading requires:

• Additional wiring for ADS-B In functionality (the GTX 345 includes an additional connector for this)
• Integration with other onboard systems such as compatible Garmin displays, MFD, or tablet
• Possible reconfiguration of existing interfaces or additional interfaces (ex. audio for traffic alerts)

For a detailed assessment of your aircraft and avionics configuration, it’s best to consult with an experienced avionics shop.