Thanks for the tag Geezer
I did find a factory tach gauge cluster. Paid heavily for it too, but it is the correct year and style for this truck. The later trucks (1983+) had different style gauges. They had white striping around the outer border of each gauge. I have one of those clusters also.

I installed LEDs for the back lighting and had to run a wire from the coil to pin #7 on the plug to the instrument wiring. The tach trigger wire is white, I was looking for the wire in the harness, but DSM did not run one. Dicks. I spent a bit of time with a multi meter looking for the wire hoping that it came from the factory. It didn't.

I have installed the cluster and also installed the original speedo into the tach cluster. Everything works correctly.
I have pix and will post them shortly.