I'm with Oakman! my horn is used at FULL BORE when in use! I don't disagree with Happy Horns though! You can just buy an electric horn from amazon or harbor freight... All it takes to wire is mount the horn where ever... I'd use power from one of your cigarette lighters in the cab and go over to the switch you buy.... (temporary on/off switch) and then other side of the switch out to the positive of the horn!
If you don't want to do it yourself you're welcome to come over and I will do it for you! If you come this weekend I'm installing an EGR/DPF delete and tuner on my dads ram 2500 similar to your massive monster! I could easily squeeze you into the bay next to him!
see you in a couple of hours?