FYI, its got 223k miles and most everything has been rebuilt, including an engine rebuild 10k miles ago etc. Has run great.

The alternator is new and battery has plenty of juice. When turning the key to crank, I can hear the relay click, but nothing after that - I.e. no cranking sound like if it was trying to start.

Inhibitor switch gone bad? Something with the ignition? I'm out of ideas but it's been a long day.