High beam not working on Silverado truck

[Rick]

@sailor

I checked the lightbulbs and, indeed they are all single filament.

You can’t swap the high beam and low beam bulbs because they are different part number due to the fact they are different wattages, and are therefore not interchangeable. So instead of trying to interchange non-interchangeable parts, how about checking for voltage at the bulb?
Also have you checked the fuses?

[Really_Not_All_That_Bright]

@sailor

OK, the truck model is LT so I guess that makes it something like Chevy Silverado LT 1500 4800. The manual lists dozens of models depending on multitude of factors like drivetrain etc. How could I find out exactly which model it is?

You shouldn’t need to know which model it is- I’m pretty sure they’ll all use the same wiring for the ancillaries.*

*unless it has a lift kit, in which case it might have an aftermarket headlight package but probably won’t.

[Gary_T]

@sailor

I guess the question would be if these lights are both controlled by some relay or fuse which I might check.

Like the high-beam relay in the underhood fusebox?

OK, the truck model is LT so I guess that makes it something like Chevy Silverado LT 1500 4800. The manual lists dozens of models depending on multitude of factors like drivetrain etc. How could I find out exactly which model it is?

The model is Silverado 1500. LT is a trim level and 4800 (or 4.8, same thing) is the engine size. Those other factors are options.