I had the charge battery light come on .Like others here while running there is a clicking noise from the alternator and a bump of the belt tensinor once in a while when the alt trys to charge . I removed the brushes found that they were not all the way worn down but did not have much travel left untill they would not be touching .Order new voltage regulator brush assmbly.This fixed the problem old brushes were worn about a 1/4 of a inch.It is iteresting that the diesel is the only car that I could find a voltage regulator brush assmbly for.

__________________

89 Ford F3504x4CC 7.3 IDI turboed Intercooler and running on wvo now powered by a 1997 Cumins
87 300SDL on bio and wvo killed by chevy truck 5-24-06
1999 E300TD black with gray int.