Ray,
I have found the following diagram for the 84-86. If this matches your current configuration, then you can do the following. The names and wire colors I refer to below relate to the '84-'86 and 1992 diagrams:
1. Remove, tape off and make safe the wires going to terminals 1 and 4 of the '86 glow plug controller (GPC).
2. Remove r/lg wire going to '86 GPC terminal 3 and attach to the '92 GPC terminal that originally had a r/lg wire attached.
3. Remove the #6 red wires from the '86 glow plug relay and attach to '92 GPC terminal that originally had the 2 yellow wires attached.
4.The '86 glow plug wires seem to have a resisitive element, so I wouldn't use those - use the '92 glow plug wire harness instead. You only need the brown (brn) wires attached from the '92 GPC to each GP. You can ignore or remove the other wires in the harness. This harness has bullet connectors for the GPs, you will need to modify those wire ends to use the spade connections on your '86 GPs.
Note that Wicked97 above says he uses an '86 harness wit the new controller, so maybe the step above ins't necessary. If your going to use the '86 harness, hook it to the '92 GPC terminal formerly connected to the brn wires.
5. Remove the BK/P wire from the '86 GP relay and attach it to the '92 GPC - same terminal as the brn wires. Your dash indicator will light whenever the GPs are energized.
Good luck.
Regards,