Looking through the archive tonight I noticed something about most of the F units, both EMD and Alco. From what I can see all the FA-1, F3A and F7A were delivered with two single chime horns, while the FP7As were delivered with what I think is a Nathan M5. Later in life as the F's started receiving 5 chime horns. It looks like the typical Leslie horns the Frisco liked to use. The shop left the rear facing single chime on most of the units. My two questions: What single chime horn was typically delivered from the factory on the F units? Why did the shop chose to leave the rear facing horn when installing the new 5 chime?
I am speculating. I have some data on the Frisco's horn preferences, but will have to search to find it. The two single horns, one front facing, the other rear facing, came from the EMD and Alco builders in that arrangement. Soon the Frisco started to remove the single forward facing horn and replaced it on the F's and FA's with a five set Leslie, all five bells facing forward. The E's also received this horn mounting. The single rear facing single horn remained unaltered on all of them. The single rear facing horn remained installed to provide some horn sound direction when the F, FA or E unit was backing up, or was running in a consist with the unit headed rear end forward. I'm not sure that the single horn was a Leslie, but it looks like it. The Frisco liked the Leslie. The FP7As did arrive from EMD with a Nathan five chime headed forward. Do not know why they went for the Nathan M5. Different sound that that provided by the Leslies. The FP7As did not come from EMD with any horn facing rearward. Some pictures I have show the FP7As with a Leslie set replacing the Nathan, but still no rear facing horn. K