i could be wrong... this is what i have observed
all my Canadian trucks from 50-53 have 2 horns, a high and low, i don't know about 49 and older yet
one of my trucks does have a 1 manifold horn and 1 horn up on the firewall
all the others (5 instances) have 2 firewall horns with those brackets
my theory:
is that it's possible the local laws required both the high and low horns up here and that's why there is always two
(and if you don't have an oil filter, then only one goes to the firewall)
since most Canadian trucks have the bypass oil filter which interferes with the manifold horn location both horns would find their way to the firewall
oil filters are so common in Canada that it wouldn't surprise me if the factory was putting in the oil filters.
one of my trucks with both horns up on the fire wall has the manifold horn wire still present inside the wire harness tapped off in what appears to be original factory tape holding the wire unused in the harness,
non of the original owners would have cared or had disposable income to make unnecessary modifications of this type to a work truck.
to me this vehicle looks like the strongest evidence that the factory put both on the firewall with a relay on at lease some canadian trucks
-s
