Mysterious headlight issue
This is a known, and dangerous situation. the headlight switch, and wiring are inadaquate for the power going thru them.
Here's some info>
http://www.oilburners.net/forums/showthread.php?t=5467
Welcome to FTE and the IDI diesel forum.
This will fix your problem and give you brighter lights at the same time.
https://www.ford-trucks.com/article/...ay_System.html




