I had a vibration between 60 and 75 MPH. Always meant to have the tires balanced. Bought the MB (1984 500 SEC) 6 months ago. Going through it as time allows. Used this forum to learn how to replace the steering box because of an annoying leak. Just completed the process and discovered on my test run down the freeway......no vibration. Apparently over the years (I have 230,000 miles and counting) worn parts in the box would let the wheels wander.) But now very smooth ride. There is also a thread in this forum in the DIY section under "steering" on how to adjust the slop (freeplay). It involves the use of an allen wrench and a closed end wrench to make the adjustment. If this is all you need to do read the thread carefully. The information tells you which way to turn the adjustment screw for tightening. Good luck.
