Wiring a Tach to MSD Ignition

[RDC]

I am about to install a MSD ignition on my 74, and it says for some tachs you will need a tach adapter, but some after market tachs will work off the grey wire. I have an in dash tach in the car, but its a 8000 rpm reproduction piece. My question is does anyone know or tried the repo tachs with the MSD directly or is the adaptor required?
Thanks

[Ghoste]

You'll need the adaptor, so far the only tachs I've heard of working direct are Autometer.

[A383Wing]

yup...shell out the other $80 or so for the adapter......

[RDC]

Ok, I see there are 2 adapters the 8910 and 8920, what one should I use?
Thanks