Originally Posted by JimFreeh

Correction:

Fourth gear in the MB transmission is direct drive, 1:1, not an overdrive.

It's not uncommon for vintage Mercedes to run at a higher rpm than you might be familiar with if your frame of reference is a lazy American V-8.

Different philosophy, MB engines can run all day at or near redline. Torque and power curves are based toward the upper range for this reason.

Later, for example the last W124s, had a low numeric differential, which essentially shifted all the ratios up one gear. By dropping the rear diff ratio (lower), you bias the final ratio lower. So, once you combine the diff ratio with the intermediate gear ratios of the transmission, you can see the "real" ratio.

Did you also notice your transmission starts in second, not first, unless you floor it or manually move the shifter into low position.

So, bottom line, the car sounds like it's doing just what it should....
So let her rev. Doesn't hurt a thing, and the cost of modifying the car for a lower ratio far exceeds and return on investment.

Jim