Honestly I will have to look ( sync box) that’s a great question. When I was trying to trace the wires I didn’t even look at that, I will be back...
So I do use a mechanical synchronizer and it works fine. The port side tach was bouncing around and then just stopped, so I replaced and wired up...
It isn’t. Just drops to zero..
I have a 1978 Post with 6-71 ( non -turbo) and the port side tach quit working. I replaced with new tach and still not working, not getting a...