Hey, I'm getting ready to buy a '68 with a powerglide. The tic toc is broken, and I haven't seen the car yet...Is the tach connected to the powerglide, or is it distributor-driven, like a Vette ? Thanks.

Tack is electric not connected to trans and can be rebuilt if found to be faulty. Are other gauges working properly?

Tach hooks to the coil. Maybe it is just bad wiring.

The other gauges are said to be working. I noticed it has an H.E.I. aftermarket dist and coil on the motor. Are there issues using the tach with this set-up? Thanks.

Yes, there can be issues with an HEI and a factory tach. A tach filter can make it work again if that is the problem.

The HEI should have a terminal made onto it just for the tach, but like Eric said, factory tachs sometimes require a filter.