How can I tell a 6 cyl from an 8 cyl tach? My V8 tach reads a higher rpm then it should. My guess is it its a 6 cyl tach. replaced in error. Thanks for any help. Jack

Welcome to the party!
There was an old post about this, I think the red line tells which tach is which?

if the biggest number on the face of it is a 10, it's prolly not for a 6 cyl.

:dontknow:

Here's the link to a thread about tachs: http://www.elcaminocentral.com/showthread.php?t=3101&highlight=generation+tachometer