IBM 704 - Manual (Page 309)

Changing Jumper and Switch Settings
The following illustration shows a SCSI drive backplane.
1 2 0
3 4 5
The connectors on the backplane are:
1 J4 SCSI ID jumper block
2 J3 SCSI ID jumper block
3 J8 Fast SCSI ID connector
4 J10 Power and ground from power distribution board
5 J15 Fast/Wide SCSI connector
6 J2 LED connector for drives 0, 1, and 2
7 J9 LED connector for drives 3, 4, and 5
8 J11 Multiprocessing-bus connector
Appendix A. Server Records 291