I too would love our 300TE to be a 5-speed manual but they are unheard of in Australia. It took me long enough just to find our very tidy wagon. Anything in a manual here is rare which is why I bought the 190E 2.3 5-speed Sportline recently (very rare combination here). I can enjoy that and my wife (who prefers the auto anyway) drives the wagon.
Possibly, in your case you could buy a good auto wagon and find a cheap manual sedan as a donor car. Beware using a manual box from a 4 cylinder behind a six. There could be a compatability issue. I know the autos in the fours and 2.6 (six) were different to those in the 3 litre and larger powered cars.
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.