1984 300sd turbodiesel

After having gotten out of class, I shifted the car into reverse and backed out of the parking space (intentionally by gravity, not by engine power). I went to put it into drive but it didn't shift no matter what. ~ I had to back it into a handicapped space (no other open spots). The only unique observation is that the shifting seems to be making a "clink" sound? Not sure if its normal or not (don't really check to hear for it, you know) What would be wrong that the car won't shift into drive, reverse, anything?

 

shifter linkage would be my first guess