i upgraded a factory Cuda ralley tach with the modern digital board only to find out that the factory movements from the period are very heavy (slow) compared to the aftermarket or modern techs we're used too.

They can be fine for reading steady state cruise rpms but upon fast acceleration they can be brutally slow, lagging behind the true RPM by hundreds. Not good for getting an idea on shift points.

I ended up mounting an aftermarket tach right in front of it.