First thing to do with this trans is drain the pan and converter, change the filter and refill with good oil and add a bottle of Lucas Transmission treatment. Drive a few weeks and then make a decision. There is a lot of snake oil out there but some do work. If it fixes it, then do the exact same thing again after about 5000 miles but use synthetic trans oil and the Lucas. I put a 89 420 trans in my 500SEL and it did very similar things. I did just what I suggested and that was about 70K miles ago. I service the trans about every 25K miles.

Paul

__________________
84 500 SEL (307,xxx miles)