I maybe wrong but I always thought the 201 16V 5speed gearbox bolted right up to the M104 engines this would surely be easier to obtain and with closer ratios then the C280 202 unit.The auto option is certainly much more popular in Europe then the manual gearbox. I have naver seen a manual C36 and doubt that a standard production version ever existed!,Are you really sure that you want to go to a manual transmission the clutch action and gearchange on the older generation Benzs leaves a lot to be desired in my opinion.The gear change when driven hard tends to be clunky and unrefined taking a lot of the pleasure from fast driving.This is an area which contemporary BMWs are far superior in which pains me to admit!
Regards Linds Hanson