Need more speed less rmp

[Heavy-d17]

so I have had my '94 c250 diesel right hand drive for a year and a bit but i need to figure out how to lower RPM at highway speeds. it is a non turbo diesel. i am not sure if there is a different transmission that i could use and if i was to change gearing in the rear end what would it take to turbo this bad boy besides the mounting of the turbo.

any help would me great

thanks

[Tomshep]

You would need the ECU, ignition switch and key to begin with, an intercooler and associated plumbing, the exhaust system and a reprogrammed gearbox. By far the best way to go would be to buy a tired 250TD in the UK and ship it over.