MSD installed..... Now the tach doesn't work?

MSD Digital 6 with the MSD TFI harness. Tach will not work unless I plug the factory coil back into the coil (bypassing the MSD). Anyone have this problem before?

This is on my 88 T/C, sorry.

You need the tach adapter:
http://natomessageboard.com/cgi-bin/ulti...351#000001

Yeah you need the tach adapter for it. I had one on mine when I had it installed.