I have an 84 300TD w/165K and have developed this same problem. For me it happens when shifting from Park to Drive or Reverse. I had a leak in the transmission cooler line on the driver's side. After replacing this it's a little smoother, but still not the way it used to be. Any ideas?

__________________
1984 300TD Turbo 156Kmi
"He who seeks knowledge begins with humbleness" - Buju Banton