It just went out on my 87 SDL at 275,000, and of course 150 miles from home.

First indication of problem: dim red anti-skid light, climate contro went to default warm air. At this point BATT was down but diesel was running.


HELPFULL HINT if it happens to you:

I removed the voltage reg. (very easy to get to on the SDL) and noticed barely any brushes with one dull brush. I pull on it with a pair of pliers and got it out another 1/4 inch. I believe I stretched the spring behind the brush because it still had positive return pressure and it was out another 1/4 inch. With a jump start after replacing the temp-repaired voltage regulator, I was back on the road.