Tom, I went to the online MB service library and checked the crank/flywheel sections. It says " The flywheel for manual transmissions with engine 617 is heaver than that for engines 615 and 616. The flywheels can be identified by different widths (dimesion "c") 617=90.0mm 615, 616 = 74.0mm. Be sure not to use wrong flywheel with wrong engine." There is similar language about not mixing gas and diesel flywheels in the other sections. I would like to find a 617 fw although it may not matter anyway since the turbo and non-turbo cranks are not interchangable. But it is worth a shot. I can't believe that nobody out there knows where to get gray market parts.
Tim