There seems to have been
one "trumpet" style Chevrolet horn.
That style horn was standard from 47-52 and was mounted on the intake manifold.
There were a variety of seashell horns, due to the paired high note and lo note, and the left and right mounts, and different mounts on cars and trucks.
The dual seashell horns were mounted in a variety of locations but the the firewall over the deluxe heater hole was the GM-designated location.
In 1953, a single seashell horn was standard and it was mounted on the intake manifold.
In 1954, a single seashell horn was standard and it was mounted on the grill side of the radiator frame.
That
eBay horn looks a lot like
this horn and
this horn.
My guess is that eBay set-up has the wrong horn mounting bracket?
