1984 Chevrolet K10 4x4 Electric trouble

Hello - My son has a 1984 Chevrolet K10, 305 cid, automatic/overdrive 4x4.
Recently it just died out on him, he said all the power died and them came
back on.  I had to tow him to get him home.  He had the flashers on while
towing but were not blinking.  The we get home and start up again.  I
changed the starter because the old one failed the test.  Replaced the
positive battery cable and get good connection now, battery is 12.7amps
plus and is about 3 mo old. Good battery ground.  Tested the alternator and
is good and all fuses are fine.  Problem is no lights turn on, get one slight
click when try to start it.  I put the hazard lights on it again yesterday to see if
they would come on while I was checking things and it did.  I tried to start it
and a slight click is all and no more hazard lights.  Seems like a wiring
trouble but need some advise on where to look.  I'm good at the mechanical
part but hate electrical.  Any advice and help would really be appreciated!  
Thank you.