And a close-up of the PCATS module attached to the factory radio.



I have a temporary extension/header soldered onto the tuner board for easier debugging.
The PCATS RF module is plugged into the extension, with a short adapter in between.

While it has a lot more pins, most of them are no-connects in this situation.
The required pins are (fortunately) in the same order as the original,
with a gap+offset mid-stride.