Tach dash differences between 1967 and 1968

[1968GT500CS]

Hello,
I bought a 1967 Scott Drake Tach dash under dash harness.  What is the difference with a 1968 car?  Can it be used in a 1968 early car, to add the option?  My dash assembly is 1968.  Trying to add tach.

Any assistance?  Anyone know the differences that matter?  Wiper?

Thank you

[Bob Gaines]

You can make it work if you have to with various modifications but unless you have some electrical aptitude you are in for a lot of stress and time.If little or no aptitude I would suggest to forget it.  You of course can compare the electrical schematics between the 67 and 68 tach harness and see what you are getting into.A 67 electrical assemblyline manual and a 68 manual would be a good investment if doing this. I believe you would be better off selling your un cut up 67 tach harness and finding a 68 one. You know of course you will have to have a 67 or 68 headlight for tach harness also.Just my thoughts others may have different.

[roddster]

You stated "trying to ADD a tach".
  If there isn't one there now be advised the the metal instrumentation backing is different between the non tach cluster and the factory tech cluster.

[Royce Peterson]

The dash wiring is different. So is the car - it may be easier to convert the car to 1967 wiring because there are significant differences. If you have electrical experience the options Bob stated are the best ones.