[Christ]

To clarify the speedo comment, Ben, if "Jim" didn't already -

Your Dime has a analog VSS electronically driven speedo. The "cedes will have a cable driven version. That'll be the only thing - getting the output of the 'cedes tranny to create a pulse signal that the speedo in your dash can read... or swapping for a cluster that still uses a cable. (Custom gauge panel, easiest, but not always cheap).

If you want to keep a manual, you could always use a chevy V8 tranny... it will hold the torque of the diesel, already has pretty long gears, and it's still manual... you'll have to find a pressure plate and flywheel that will fit the engine though. (good luck)