Mike's answer is spot-on. No matter how much research you do there's always that chance that the locomotive you want to model has had it's horn changed at some point in it's history.
Often, horns were prone to clogging or getting dirt in the "power chamber" where the diaphragm is. For the sake of convenience, whatever horn is on-hand may be substituted.
Here is a general list of horns used by certain railroads from Soundtraxx.
http://www.soundtraxx.com/choose/choose4.php
Here is another site where you may find a photo of the Rio Grande locomotive you want to replicate:
http://www.rr-fallenflags.org/drgw/drgw.html
Good Luck, Ed
Rob,
It varied. Nathan was pretty popular (M3 and others) but there were different ones depending on the purchase era and the unit. In some cases, there were changes made in service, so if you need complete accuracy, you need to do some digging or come up with a pic to document what was on at any particular time.
A good selection of answers can be found here (and I think you can view the various threads without joining the group): https://groups.yahoo.com/neo/groups/DRGW/search/messages?query=air%20horn
Mike Lehman
Urbana, IL
Hi all
I have tried a couple of searches on the net as to what type of horn was used to no avail.
So is there any-one here who can tell me (and hence others) which air horn was used by the DRGW, or did it change over time or with different diesels.
Thanks in advance
Rob