The #1 Bell has the IEC-Holden LTD tag on and is sandcast, along with the #2 bell and originally the #3 bell would have almost certainly been, but must have encountered an accident and so is currently a diecast narrow font replacement.
The serial number places it around 1975, right at the end of the sandcast period, and explains why it has wide font backcaps - the 'Made in Canada' backcaps ran out shortly before this horn was manufactured.
The other interesting part is that the original high manifold was swapped out for a low manifold, for whatever reason.
The bells have a number '1834' scrawled on them in large permanent marker: this makes perfect sense as locomotive #1834 was a Montreal Locomotive Works (MLW) RS-18u, built as #8776 but rebuilt to #1834 in 1985 by CP Rail. It was sold to New Brunswick East Coast in 1998 and then scrapped in 2009.
