Drivers Side Rear Grating 450SL

[GAMMTKA]

This irritant started about a week or so ago. When exiting my parking ramp I noticed a squeaking sound coming from the rear drivers side wheel area as I turned right to go down the exit. The sound got progressively worse over the next days/week. Now, there is a metal scraping sound coming from the same area. This sound comes and goes while driving - a couple of minutes on and a couple off - it seems to be a slower sound that one that would come with every revolution of the rear wheel. I've searched the forum and think it might be the u-joint. Does this sound right? Although I am capable of some repairs myself, this one has me concerned that whatever it is is beyond my abilities. Any suggestions on troubleshooting techniques to isolate the problem? If I have to take it in to the local MB dealer I would like to have identified the problem. Also, do you think it is safe to drive the 10 miles to the dealer? It's a 1976 450SL that otherwide runs super.