Nathan Airchime P5 (P135R24) [Possibly NOS]

I acquired this in an estate sale. I was told the gentleman worked for Canadian National Railway (CN) in Toronto, Ontario.

It’s in great condition and doesn’t appear to be weathered at all. However - there are markings on the base that indicates it was bolted to something at some point. Could be NOS (New, Old Stock) but I have no way of knowing for sure.

The base casting has “Model P” and “21061” on it. Horn castings are as follows:
P1 21056
P2 21057
P3 21058
P4 21059
P5 21060

According to this page, it is a model P135R24 as horns 2 and 4 are reveresed.

Looking to sell for $1500, open to offers.

I am located in Oshawa, Ontario. I can ship if needed.