Audio board J1
Cpu 1j15
1j18 (but i believe this remains blank)

AUX pwr board
J9 (i believe this remains blank)

Inter connect board

J16
J20r

According to the pages listed previously;

Audio board
J1 should connect to CPU J16

CPU
J15 - not connected
J18 - not connected.

AUX Driver Board
J9 - not connected.

Interconnect Board
J16 - should be a 3 pin, 2 wire plug from the drop target opto board.  
J20 - not connected.