TOPIC: 1967 Merc 950SS tach install?

I have an aftermarket CDI ignition in my 950SS. It does not have a tach output at the switch box. Can I connect a tach to the rectifier? If so, which tach (or specifications) do I need?

Thanks!

You will need a tachometer that has the option of reading off a 12 pole alternator (stator). It will either have a "6P" position, or a position "4" that is identified as being for a 12 pole alternator.
The '6P' should not be mistaken for the "6C" as they are different.
You will attach the 'SEND' lead to either yellow wire on the rectifier. The "SEND" terminal might be labeled "SIG" or "ALT"
doc

Thanks Doc! Any idea what vintage tachs will work? Or am I stuck with a newer one?

Here's a link to the AirGuide tachometer buyer's guide if that helps any?;
www.classicboatwork.com/classicparts/gauges/airguide/airguideinstructions/Airguide%20Tachometer%20Application%20Guide.pdf

Thanks Mark. Looks like my options are the 651, 655 and 685 then. All these should work on a 6-cyl, connected to the rectifier, correct?

"All these should work on a 6-cyl, connected to the rectifier, correct?"

I don't think that is correct Norm, but wait for one of the Airguide Wizards to reply.
doc