Tachometer circuit board repair kits
The factory tach in my Barracuda worked but was extremely slow responding. I could rev the engine to 4000 rpm with another tach and the factory one would be barrely past 2000 when I backed off. Given time it would catch up and read accurately. I called RT about whether their board would fix this and was told no.
I went for an after repro tach from Year One. They had tw different dial faces and I am not sure which one was correct for my car but the tach works great and looks good in the dash.