I'm not into this performance business but thought I'd share a website I stumbled through. Swedish manufacturer STT Emtec has been making turbo kits for the 240D (OM616) for a long time, and their site still lists those parts as available.
"Spare parts are available, while stocks last, for the models below"
http://www.sttemtec.com/index.php?show=752_ENG

Phone no. and mail found at very end of page..

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Tomas, Sweden
1966 Mercedes Benz 230S with OM617.912, automatic. Disk brakes from W108
1983 Mercedes Benz 300TD grey, OM617.912 and 5-speed manual
1983 Mercedes Benz 300TD blue 7-seater, OM617.912 and 5-speed manual