I don't have the build sheet but even if I did I know the car has had modifications. According to what I've read the buzzer was available for it. The wiring harness does sport the wires for one.
I do know that the car did not have a factory tach when it came from the factory despite the fact it has a 4-speed. (it does have a new tic toc tach now that has never been hooked up) It was also a stripe delete car.
When the previous owner rewired the car he may have routed some of the wires for the buzzer into the circuitry whether or not a buzzer exists. I'm not sure if I can leave that yellow/black wire disconnected on the one end without having problems with whatever else it may be routed through.
I was using 3 different schematics to help trace down the wiring. None of the 3 were 100% accurate with the wiring that's in the car. The one that was supposed to be specific for the Roadrunner lacked the grey wire showing the tach hookup. I still focused on that schematic the most but had to reference my schematic for '68 Chargers to find out what that grey wire was for.
I worked as an electrician on industrial equipment in factories for years but I'm weak with automotive wiring diagrams. I'm used to working with large blueprints that were easier to follow than these small ones that are on several pages. I'm not used to working with schematics that show devices that may not actually be there either.