Irritating electrical problem

[72c20customcamper]

I had the exact same issue .My turn signals indicators were wonky on my 68 but only with the high beams on . Sometimes they just glowed other times if I turned the right blinker on the left indicator would blink and the right one would stay dark and it was reversed if I put the left blinker. Outside the lights worked normally . I tried grounding the dash instrument pod that did nothing . I then checked all the grounds on the truck . It ended up being the ground at the radiator support on the drivers side . Cleaned up the contact put some electrical grease on it a retightened the bolt with a new washer. Works perfectly now