I jumped the two mystery wires at the connector, and my dash green indicator
light for the differential lock shone again after a two year hiatus.  Since
the diff lock no longer exists after the transmission rebuild, the rebuilder
had obviously cleverly hidden the indicator wire, which I failed to uncover
until recently.

Sometimes the simple solution is the correct one.  Thanks to all for their
help and suggestions.
Budd Premack
86 Syncro, 73 Super
Minneapolis, MN (Land of Sky-Blue Waters)