10.  The left-hand backing plate on the back-side of the housing is removed to start the tach installation process.

14.  The tach wiring harness has three wires.  The pink wire connects the tach to the ignition/power terminal located in the fuse box.  The brown wire connects the negative post on the tach to the negative on the coil.
 

11.  GM used a blank gauge to fill the void in the cluster on non-tach models.  The new tachometer gauge simply replaces the original blank or dummy gauge as they were called back then.

15.  The light-bulb socket on the gray wire plugs into the center hole of the tachometer housing.

16.  Along with the tach conversion kit, Early Classic also offers replacement dash components such as the knobs, switches, and cigarette lighters.

17.  The newly assembled tach dash re-installs back into the truck in the reverse order that it came out.
     And there you have it, a factory-style tach dash in less than a few hours work.  This upgrade is simple to install and adds a whole new look to the dash of our truck.

SOURCE

EARLY CLASSIC ENTERPRISES
5843 E. Clinton Avenue, Dept. CT
Fresno, CA  93727
(559) 291-1611

12.  Since it is impossible to read the terminal identifications on the back of the tach once it has been installed onto the backing plate, the guys at ECE recommend marking the wire connections prior to installation.

13.  The new gauge comes with clip-on arrows to mark your high and low-rpm shift points.  These are optional, but if you decide to use them, they need to be clipped on before the tach is installed.  The new assembly bolts right back into the main-cluster housing.