Is anyone using MS-3 and driving the stock tach with it?

A lot of the aftermarket tach output is a lower voltage signal. Our early stock tach uses a 12v signal. You can use pretty much any 'Tach Adapter' such as the one from MSD. This takes the low voltage signal and steps it up to 12v. You can also use a late tach, which seems to work out of the box, but you lose the 'silver dot' if that's how your gauges look.

You can also have your stock rebuilt with new internals. Or do it yourself, using a donor tach.

As seen here

What Mark said.
My MS will drive the stock tach just fine on my car, but my car has a 75 build date. No changes are needed if you have a later tach.

Zach

I have an extra msd tach adapter