72 swinger 318/904 ac/heat ....What car, year, options etc......
I've got the holes that thing left behind I wonder what it was tooI recall seeing a similar-looking device in a recent post, also asking "what's this". I recall that was a later car ~1975+ so may not apply. I also don't recall the answer. I think 1972 was too early for the seat-belt ignition interlock relay (under seat anyway I think). Your hot-water diverter valve near there should be vacuum-operated. The horn relay looks similar, but usually on the driver's side. Might have to do with the heated choke system.
Thanks again all We don't need no stinking emission devicesEmissions device. In 71 they were on certain combination N95 coded California emission cars. Don't know if that changed to all cars in 72.
That had other devices included depending on trans and motor.