So, I got my 1985 GT (converted over to EFI with full 86 harnesses) fired up for the first time last night, and it runs great, but has a few wrinkles to work out.

First is the fact that my factory tach is not working. After some research, it looks as though I may need an MSD Tach Adapter, part number 8920. I am running an MSD Digital 6 (not to be confused with the 6A or 6AL series MSD systems), and I am having a tough time finding accurate info as to what I need, and how to connect it to my car. I called MSD today, and they said that they couldn't give me any specific information about how to wire it to my car, but they said just don't connect the Tach Adapter to the coil... AT ALL. MSD shows wiring diagrams to connect their Tach Adapter to a 6A or 6AL, but nothing for the Digital 6.

This was especially confusing, as I thought that the tach lead in our cars connected to the negative side of the coil.

The Digital 6 has a tach lead connector, so I can wire the Tach Adapter to that, I just need to know what signal wire I need to connect the Tach Adapter to, so that it will send my factory tach the appropriate signal.

Hopefully someone has been through this, and can help out.

Thanks in advance