Looks like we both in a similar boat. Do you have pics of the Benz?

My 1980 300sd had a replaced trans, where they overfilled the trans fluid by about 10oz to much removed all of that, and she clicks through much smoother now, but as you said the 47mph for 4th gear is a problem for me as well. I got under the trans, and found that the connecting rubber hose for the vac modulator and the line was nearly dry rotted. I found a similar diameter hose (slightly larger) and slid it a decent ways up the vacuum tube and attached it to vac modulator and that helped remedy the problem for a temporary fix till i buy new hose