greetings, I recently ran into these parts when I was doing a little drive shaft work. In my car, 123 300d, the long threaded bars slide up in the chassis for the drive shaft bearing mount.
The bolts look about as short as mine, bolt through the bearing holder, looks like a pillow block, and hold the drive shaft bearing up into the driveshaft tunnel. I haven't run into anything similar anywhere else. My description may sound convoluted but without looking at a repair manual for the proper terms Its the best I can do. besides it was a PITA holding the shaft and bearing in place while I threaded in those short bolts. The threaded bars kind of float around until they are captured by the bolts at just the right angle. hope this helps. cheers, mark