> My Ox and Alt lights have both come on and gone off together the whole time I have owned 
> this 1985 van. It is on its third alternator, and running its second reset on the Ox milage 
> meter. The lights stay on when the van is first started, and don't go off until the rpms rise 
> over about 1.2 to 1.4k. Seems to depend on temperature or battery state. Grounds have 
> been checked and cleaned, in fact the instrument cluster is a replacement. Same 
> symptoms since the start.

Have you checked the condition of the blue wire from the back of the
alternator to the dash? The might be a corroded, crusty, crabby, or
loose high resistance spot along that blue wire somewhere that's
bringing the reported alternator voltage down below nominal battery
voltage at lower RPMs. Goven the multiple new alternators and the new
instrument cluster, it sure sounds like the wire is all that's left!