Ok, I just got a '72 K5 not long ago. Whenever I drive it, I hear what sounsds to be the 4-way flashers on... a clicking from the dash. It starts and stays for a minute or three, then stops. When driving after dark, I noticed the instrument cluster lights flash with the sound, and so do the turn lenses outside. But the flashers are NOT on. If I turn the flashers on, then there seem to be two separate electrical signals going to all the lights, with the 4-way flashers being a bit greater in intensity than the mystery flashing. (the 4-way flasher and signal light indicators only flash when the signal lights or 4-ways are on, but not when the mystery flashing occurs). It only begins to do this when I am driving it or it is running, and is totally random (I havent linked any patterns to when it starts doing it yet). If I shut the motor off, it will continue to flash (and click) until it decides to stop. While driving it, it will start and stop numerous times with no identifyable pattern (yet). Has to be some electrical short somewhere.