There are threads on BW that walk you through stuffing a pre-00 722.6 case with beefier internals from a later 722.6. MAVA will hold your hand through the process -

https://www.benzworld.org/forums/w210-e-class/2997317-97-e-420-transmission-rebuild.html

Sixto
98 E320s sedan and wagon
02 C320 wagon