IFD540 swap for GNS530

Good afternoon. Trying to assist a friend with a recent aircraft purchase and conformity issue where the original GNS530 was swapped out with a IFD 540 by the previous owner/pilot as a preventative maintenance action per an "Avidyne Exchange Guide" and Part 43. However, in the IFD540 Installation Manual (600-00299-000) I have access to under the 2.1 "Plug and Play Considerations" section it lists several requirements that would prohibit this type of swap by an owner/pilot and require the signature of an FAA A&P as an alteration.

It's my understanding there is no FAA LOA for this swap per the "Guide" and a couple Avidyne dealers the current owner talked to both recommended the swap should be performed by an A&P. Given the IFD 540 unit appears to only have STC and TSO approvals vs a standalone PMA, the IFD 540 appears to lack the requirements to be considered a straight part replacement for a GNS530 per Part 43 Appx A(c)(31) as noted below.

Is there any other Avidyne or FAA documentation available that would offset the Installation Manual information and requirements or give approval to use the "Guide" that I am overlooking? Any assistance would be greatly appreciated.

Part 43 Appx A(c)(31):

Removing and replacing self-contained, front instrument panel-mounted navigation and communication devices that employ tray-mounted connectors that connect the unit when the unit is installed into the instrument panel, (excluding automatic flight control systems, transponders, and microwave frequency distance measuring equipment (DME)). The approved unit must be designed to be readily and repeatedly removed and replaced, and pertinent instructions must be provided. Prior to the unit's intended use, and operational check must be performed in accordance with the applicable sections of part 91 of this chapter.

The pilot done swap out procedure was outlined and made available by Avidyne to move from a GNS to IFD.

* Orest

Is there traceability for, say a stolen G 530/430 that a crook could use in Avidyne’s trade in program? 7 airplanes have been vandalized by someone who knew how to remove radios from their trays.