Thanks for the lead. My S-10 is not wired for a tach and the Cluster was purchased on Ebay for an 82 Elky that I have given up on. I have not made any measurements of the cluster but visually it is about the size of the S-10's cluster with the Malibu's shroud cut away. To be honest I don't need the tach, but if it is there, I would be wise to make it work.
The wiring diagrams on this site show the tach signal originating at the distributor. I could make the assumption that the connection is the male spade next to the distributor hot wire. I don't wish to be the "a-s-s" in assume.