I've answered my own question about a standard cluster with a tach added. It WILL NOT work. I purchased on of each and the circuit boards lighting and alignment don't match. From feedback from my last thread, evertone was correct. The only way is to modify to a tach harness. I will be changing my cluster to a standard setup and add an after market tach. I've already added gauges into the center bezel so warning lights are gone. No sending units. This car has nothing per the build sheet so I'm learning as I go.
I would hang on to your tach cluster. You never know when parts will pop up--you may find the tach dash harness when you least expect it.
1931 Ford Model A Station Wagon
1969 Mach 1 - 351C, TKO-600, 4WDB, R&P, A/C, Shaker, Fold Down, etc.
1972 Mach 1 - 351C, FMX, PDB, PS, A/C, Fold Down, Console
1996 Mustang Cobra Convertible - 10psi Procharger
You should be able to get the circuit board for the factory tach - I've seen them for sale somewhere (CJ or OMP - can't remember which). If you want to get rid of the factory tach cluster, let me know - I'm looking for one and I don't mind getting a new circuit board or whatever to make it happen.
As well - how does one go about pulling the instrument cluster, anyway. I have all the mounting bolts removed, but I'm stuck on the plug and speedo cable. Does the cable connector push/twist and unlock, or does it unscrew (like my '82 did)?