My '75 GMC K25 does not have a factory tachometer, but I've located
a Suburban (74-76 vintage) that has a full cluster with the factory
Its still installed in the vehicle and appears to be complete.
Will my factory wiring plug directly into the cluster that has the tach?
The tach cluster moves the fuel gauge to the clock position, and deletes
the clock, but my guess is that the plug for the wiring is the same.
I have the Chevy manual for 74/75 pickups and it shows a tach wire as
an option, but doesn't show where it runs.
What additional wiring do I have to run to make the tach work - just
a line to the tach output on the HEI?