Looking at early photos of Frisco's GP7s, they appear to have Leslie Tyfon A200 air horns when delivered. Then they were replaced with the Leslie Super-Tyfon's after 1953. Would someone be kind enough to confirm or correct me on this please?
I think you are essentially correct, though I'm not sure what the as-delivered GP7 horn model was. One was mounted on the side of the short hood facing forward on the engineer's side. Another facing to the rear on the other side, but back a bit on the side of the long hood, just aft of the first radiator grill. The Frisco did not think they made enough noise, so in 1952 they conducted a series of tests on replacement horn models and different locations. The Leslie S-5T-R was the winner. The Frisco used them for years in various configurations, mounted on the cab roof right of center. Other horn models were used here and there as well. I have seen several GP7 pictures that clearly have a Nathan M5 mounted up on the cab roof. The Leslie was the favorite, though. I think somebody in the SLSF motive power department must have had an ear for music as they chose the most melodious horn. Ken
The as delivered single chime horn was more than likely the Leslie A-200 as originally suggested. The only other option would be the Wabco E-2 which is very similar. The Leslie horn was by far the most common on an EMD. The Leslie S-5T probably won out because it required much less maintenance that the Nathan M5. Another factor could have been the lower notes that came from the Leslie. They tend to carry a longer distance than the slightly higher notes of the Nathan.
