Guys- Thanks, I have the exact same noise- started yesterday in my79 300d- The heat shield started rattling like crazy last week. I was going to attack it today, but the noise from hell changed my plans. It is hard to believe that the noise is not coming from behind my dash, but I will look as soon as the temperature climbs a bit.

 

Try to get to it quick .... if it was anything like mine all I needed was someone heavy to sit in the pass. seat and it would have started wrapping around the drive shaft untill it took out the whole thing.....