Clicky starter is:
Single or multiple clicks when the ignition switch goes from on to start.
Sometimes just a slow reaction when the key is turned before the engine starts.
Caused by original wiring configuration where the power comes from the battery, or starter hot connection, goes through the ignition switch, then back to the starter solenoid.
The fix is a simple 20 amp relay that goes from battery hot directly to the starter solenoid. The relay is engaged by either a wire to the ignition start terminal or the relay may be always hot with a ground button placed inside the cab.
Simple & inexpensive fix,