93 Le Sabre won't start but have full power to lights and radio?? WTF?

Replace the battery cable with the stripped nut, obviously not enough current is getting to the starter to engage it, all you hear is the solenoid clicking, the battery cable connection needs to be very tight to work properly. You may be able to find just the battery cable end and replace only that, take a look at your auto parts store and see what they have.