My former '90 300E had 175K when sold. Transmission was fine. My '92 300E has 232K, and shifts exactly like it did at 113K when I bought the car. Fluid and filter every 30K.

I subscribe to this bit of logic. What wears out a transmission is shifting. The shifts per mile for my driving situation are low. Around 90% of the miles are long interstate trips of roughly 8 hours. No wear occurring if it's not shifting.

Steve