"I can't remember where the relay even is"

I hear you!!!

Its under the dash just left of the steering wheel. The FSM actually has a good troubleshooting section for horns. Bad ground most likely the culprit Scratching that beautiful paint to bare metal is never easy.

Scott

70 Coronet RT 440+6
64 Dodge 330 - Future Hemi Clone
17 Challenger Hellcat - Green Go Driver
86 Buick T-Type Turbo V-6