I dont' have that diagram, but I know what he's talking about. When you turn the key, the ignition cylinder pushes a metal rod, which activates the ignition switch further down the column. It's not like modern cylinders where the switch is on the back of the cylinder. Ours are bolted to the top of the column.
You can google mid-80's Chevy columns... they're almost identical. Will probably give you more picture options until you get the FSM. If you don't mind me asking, how much was the FSM? I need a copy for the wiring diagrams. I have Snapon's "Mitchell" program but the diagrams are poorly scanned junk until '97...
'91 Frankenheep YJ. 4.0, 4" BDS, Richmond 8.8, Titan 12k, 35" KM2's, rust.
'88 YJ, 4.2/4.0 head, +4½" & shackles, BFG 33's (sold)