IIRC the company was Dixco? that made the hustlestuff hood tachs. I almost bought one a couple years ago for a 71 road runner.
The pontiacs were big on hood tachs.
They look cool but are a pita. They are hard enough for the driver to see much less a guy in another car!! Plus they tend to leak moisture/condensation, etc.
If I ever get a road runner without an interior tach I'll get one though.