there is a transmission that can be mated to the 2.5t engine, and thats a crosworth 5-speed from a 190e 16v motor.
the guys at this site seem to know how to do it:
http://www.teamrwd.com/dieselboost/250.php
http://www.teamrwd.com/dieselboost/300_24.php
http://www.saunalahti.fi/~hecekiel/dieselboost_demo.mpg
i know its a crosworth because in the video you can see the stick shift pattern, with 1st where 2nd normally is. the great thing about mercedes is the interchangability between motors and transmissions. you could take a 300sdl motor and mate it to a 16v transmission, if you wanted. (i think thats what they did with the black car).
too bad its in finnish or something. but i bet they speak english if you emailed them.
as for parts references, mercedes has an online service called startechinfo or something like that. i believe it includes all makes, models, years, parts catalogs, and repair jobs. it is a pain to use but all the info is there. you pay for the online subscription by the day, so have a fast internet connection and a laser printer handy.
i cannot find the link by i will post it tomorrow from the garage where i have the link saved.
i think it would be really cool to buy a 190e 16v with a blown motors and swap in a turbodiesel. might as well upgrade the turbo like they did too!
good luck.