confirm that the rod that runs from the multifunction stalk down the column to the hibeam switch is there and engaging the switch. I've had them get out of alignment before. you can also check for power there.
@cruiser54 any ideas?
sounds like it's time to pull the harness off the headlight switch and inspect for melting too. checking all the high-amp connectors is part of regular maintenance on our old trucks. (hvac, steering column, blower motor, blower resistor pack, etc)
it's only 6" in front and 6" in back of the rear tire. you'll never notice the change (until you're loading stuff in the bed and find out it holds 16% more. )