I have seen this posted before but don't beleive my 83 has all the pieces the 300D's have.

At full throttle shifting is smooth although it seems acceleration stops a few seconds befor the last shift at 60.

At partial throttle shifting can be neck snapping.

I see from other posts vacuum leaks are suspected so I looked at all the hoses. There are some black rubber hoses connected to two switches mounted on the valve cover. They seem rather loose. The output of the switch goes to the transmission.

__________________
1991 350 SDL
183,000 miles

1982 240D
130,000 miles

First you might plug in your car to these two sites and see if any updates have been issued by MB for that situation....

http://www.nhtsa.dot.gov/cars/problems/tsb/central2.cfm

http://alldata.com/

I know some changes in vacuum force adjustment for the modulator have been listed there for other early 80's MB's...