Dear Sir:
I am currently working on a 1974 280C. When the key is off the charge indicator light stays on and it will run the battery down over nite. I realize there are limited circuits which are live when the key is off, but do you have any ideas where to start. I was thinking about pulling off the alternator and having it checked. Any suggestions you have would be appreciated.
Thanks.

You probably have a bad diode in the alternator. Try disconnecting the wiring from the alternator to verify. Be sure to insulate the positive feed wire.

I just fixed the exact same problem on my 74 280c
 

I had a bad diode. I picked up a rebuilt distributor and swapped them. before that, I just tried swapping the voltage regulator, but it didn't help.

-CTH

PS. Be VERY careful with that positive wire. First disconnect the battery. Short that wire to ground, or have the wrench touch something and the results will be very messy.

Dear Sirs,
Thank you for you response. I removed the alternator and the rectifier was shot. I purchased a new one and it solved the problem. Once again thank you.