1) I have a nice 1987 22-R, base pickup, 5 spd MT, with California Emissions, and I have an inoperative headlamp warning buzzer and want to restore its operation. My FSM says it ought to be located around the Emissions Computer behind the passenger side kick panel. Is that where it is? Is this feature an option that may not be on this truck?
2) I'd also like to find out if my truck has seat belt warning buzzer. I searched under the seat and carpet (both sides) and there is no wiring near the buckle part of the seat belts at all. Federal law says there should be such a buzzer.
3) The only buzzer I hear right now is the one that sounds off when I turn the ignition off and leave the key in the lock cylinder.

 

If you looked and it's not there, your truck probably doesn't have it, just like mine...
I made my own:
https://www.yotatech.com/forums/f199.../#post51903481

 

^^ Yes, the headlight buzzer was optional. Most trucks that I have seen do not have it. My 1987 2WD Truck doesn't have one either.

The seat belt warning buzzer is the same buzzer as the "key left in the ignition" buzzer. There should be a wire going to the driver's side seat belt buckle.