Clean the inside of both battery cable clamps until they're bright and shiny, and do the same thing to the battery posts. You've got an almost, but not quite open circuit from dirty connections that will carry the load of the gauges but not the heavy current that starter needs. I've seen a few hundred vehicles with thre exact same symptoms, and cleaning battery posts and cables fixed virtually all of them.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!