I really do not know, at this stage. Do the PDS slots look any different? I need to compare what signals are present. My guess is that the second PDS is interfacing with the 030, so it is not really passing through to the same bus. For now I will get a pinout and when I open it again in a week or two try tracing the connections on the board.

Also I was up late working on both my SE and my SE/30 so my recollection is a bit jumbled.