Early Raised Letter K5H (ex UP) Train horn

Here's an early raised letter K5H, double tagged and stamped to indicate union pacific RR. (not my horn) It was sandblasted by the previous owner, but traces of the original gray paint remain. Early RL 2 bells are unbored and thus play the same note as a NF 2 bell, giving the overall horn a unique tone. Oddly, the 5 bell was machined with Metric threads as opposed to imperial, incidated by the "M60" etched on the side. Not sure how common those are.