As to PCAS, in Europe it is illegal to hard wire these systems into an aircraft because they are not certified for panel mount by the regulators. Many people do, but that is another matter. If the unit is plugged into an adapter socket then it is not hard wired. I doubt any regulatory authority would certify either of these untis to be hard wired into an aircraft but who knows what might or might not be allowed (particularly in a combat zone - sorry I just couldnt resist. but I am only joking).
The work was done as an FAA field approval, major repair or alteration. Everything was legal. That's all you really need to know.