I have a strange set of lighting issues I can't figure out.
First one: Daytime running lights come on when truck is started. They remain on when parking lights are turned on. Switch to headlights and they go out. No low beams. High beams work.

Second one: Front turn indicators aren't consistent. Sometimes the front and side lights blink in sync, sometimes they alternate.

Third one: This one is weird. Reverse lights are doing their own thing:
Right turn signal on: both reverse lights blink
Left turn signal on: no reverse lights on
Gear selector in reverse: middle light and reverse lights on both sides
Gear selector in park, step on brakes: middle light and reverse lights on both sides

I have pulled out and verified the wires for the tail light assembly that runs by the back bumper, and removed the ground by the spare tire and cleaned it up and fastened it with no change.

Can anyone please give me some idea of what is going on?

the housings on the 88-98s there is a circuit board there that can cause the signals to cross as they go out, check it out they are sometimes pretty obviously corroded and i think they have dorman help boards at the parts store now, though they didnt when i needed them i had to buy whole ones. might be ten years ago though

You were right about the circuit boards. I bought a set and replaced them, which fixed that problem (3). Next major one is the headlight issue.

Changed out the headlight switch and no change. Low beams still cut out when turning the switch from parking lights to running lights.

so you have drl and high but no low? check to see with a meter if the low socket has power and good ground?

I tested the dimmer switch using this proceedure: Part 2 -How to Test the Low-High Beam Headlight Dimmer Switch , and the headlight switch using this one: Part 1 -How to Test the Headlight Switch (GM 4.3L, 5.0L, 5.7L) . Both tests passed, but I replaced the headlight switch anyway. I got the low beams to come on by slowly turning the headlight switch to running lights a few times, but they went out a few minutes later. I am thinking it might be the DRL relay.

Replaced the DRL relay down by your left foot (not the diode brick near the center of the dash). Low beams are working so far.

Thanks for following up and letting us know what seemed to fix your issues, if there are any changes let up know.

Will do. Hopefully this will help someone else to not bang their head against the wall as much as I did.