Thanks, everybody, for kicking in,
I do have a service manual, just not sure where to start looking, when nothing at all beyond the clock-dimming is happening.
I will check the fusible link. Would the clock light at all if it was severed?
I don’t leave a battery in the truck, just swap one in when I need to use it, so I’m sure the battery is good and the connections are tight.
Also plan to check more relays, like the main relay, now that I know how (thanks again, Eric), and will report back with results.