Thanks Jim.  I appreciate the effort on your part to provide a link - it's more interesting to me than just giving the answer.  I should have searched it out, anyway.

Spoiler alert!  (just the answer)

 Regarding adding a tach to an 80 - 84:

		
	
	
		
			
				
					20. String a wire (16 or 18 gauge is fine) from the Cluster area to your Engine Compartment. Connect the Engine
side of the wire with a 1/4” Female Push-on to Terminal #1 on the Ignition Coil. This is also known as the NEGATIVE
side of the coil. from:

 http://www.oldvolkshome.com

Skip
ps.  I bookmarked it, but I might of bookmarked it already...