What's the context? Is it part of a route, or something else?
If it's a horn or engine sound, it can be easily substituted with something else. The same with route parts such as trees, buildings, etc. Track can be painful, but that is similar.
If it's another engine or train car component such as a bogey that can be a bit more difficult and may not be worth the effort in the end anyway.
Have you tried Google, Bing, or the TKI?
