Speed does not match revolutions per minute – gears KO?

Hello all!! I have a 500SL (R129) built in March 1992 quasi “herited” or took over. The car has a few “light” quirks, but still makes a very good and clean impression. Drive now for a few days with it and have found the following, for me very strange, problem. I was surprised that if I speed up with full throttle The car turns up to 6,500 – 7000 (red range) revolutions but the highest speed for the respective gear still does not then I recorded the speeds at certain rotations and compared them with videos on Youtube and found that my SL was definitely turning too high. Following approx. values2. gear 3000 UPM -> 45 km/h 4000 UPM -> 62 km/h 5000 UPM -> 78 km/h 6000 UPM -> 95 km/h 3. gear 3000 UPM -> 70 km/h 4000 UPM -> 95 km/h 5000 UPM -> 120 km/h 6000 UPM -> 145 km/h 4. gear 3000 UPM -> 100 km/h 4000 UPM -> 135 km/h 5000 UPM -> 165 km/h 6000 UPM -> 200 km/h It’s hand It’s about a 722.3 (4 gear) gearbox which otherwise switches completely normal (drive other MB from the 80s and 90s for comparison). The car also has thrust and accelerated, my eighth, normal. It’s just as if the gearbox had a shorter translation. What could that be? On the torque converter? I’ve been looking for information and remedy for days, but I couldn’t find anything until now. Would I look forward to any feedback. MfG, David.