Msd vs Tach

There is a tach output terminal on the side of the MSD box. If you look at the table in the MSD instruction sheet it will tell you generically by brand if the tach will work off the terminal by being directly connected or whether you need one of the two MSD tach adapters they sell to make the tach work.

If you need an adapter it will likely be just as cost effective to pick up a tach that will work off the tach output without the adapter.