I think I know the answer to this, but hoping I'm wrong. On the Digital Dash, the I/O grounds B14-B19, it says that B19 has to be grounded for RPM and gauge function when using the tach signal from the ignition box. Are B14-B19 like a bus bar and one port needs to be grounded? Is this for RPM gauge only or all gauges?

Reason I'm asking, I'm out of ground positions, and already have other sensors sharing grounds. I'm ordering the Holley 554-131 Tach Input Conditioner, and was looking over the instructions and it states to connect the black wire into one of the grounds B14-B19. Does B19 still need to go to battery/chassis ground? Thanks, Mike