thanks HO455 and LockDoc. I'll test out the resistance of the two coils. I'll see if I can trace the wiring from the resistors as well to possibly find the elusive relay. I have an all-inclusive manual 67-72 Haynes manual I'll look at too for inspiration.
At the moment I'm installing power locks from A1 Electric, and have the usual stumblings with running wires around the whole rig. Maybe I'll get lucky and run into the relay during that!
