Any tach from any four-cylinder car can be made to work, but since my time
is worth more than that I would limit it to VWs of the same year range. Most
of the instrument cluster is interchangeable, my '84 now has a nice Jetta
tach (instead of the original clock).
Installation, AFAICR, was simply replacing the back cover of the tach (I had
already modified the wiring to later bus standard).
You do have to remember that your redline is not the same as the Jetta's,
though.