Speedo Mystery Module

[FritzA]

Some of the Autometer electronic speedos already have an output terminal on them to send to the ECM or to cruise control. You have to make sure the output is compatible with what is needed.

Or

Dakota Digital makes a little box that takes input from the electronic speed sensor and has multiple outputs for electronic speedo, ECM and cruise. The outputs are also adjustable so you should be able to get what you need.