I had the exact same thing hapen to me about a month ago. Not sure if the SD tach wil work or not, but common sense thinking tells me it should. Just look on the back of your tach and see if the electrical connector is a 2 pin or a 3 pin.

Mine was a 2 pin style so I ended up getting a used 300D 2 pin tach off E-bay.

Good luck!

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)