Here's a pic of Min By Eric's HO version:

The N pix on the site, to be nice - suck. This has always kept me from ordering anything from them.
There is no Leslie S-5T correct for N&W, so for the Southern SD24 5 chime stands in until something better comes along.
The S-5T was a popular horn on Kansas City Southern, Illinois Central, MKT, Norfolk & Western, Frisco, and Chessie System. Santa Fe used the S-5T on most of its passenger diesels. (N&W used a "S5T-RR" - Details West makes it in HO >

)
from:
http://atsf.railfan.net/airhorns/s5t.html