In fact, one could remove all of the components and the interconnecting wiring and provided that the overall configuration remains the same in terms of LRU part numbers, the installation / system remains unchanged.
I see.
So if I remove the antenna and replace it with the same part number/mod status, remove the antenna coax and connectors and replace them with the same part numbers/mod status, remove the mounting rack and electrical wiring and replace them with the same part numbers/mod status, and the remove the TX/RX unit and replace it with the same part number/mod status, I have
not installed a "replacement ... system", even though I literally replaced the system.
I only install a "replacement system" if I install a system that has different part numbers?