John, thanks for writing and for watching our forum/website. I don't know the answer to your question, but I recommend that you contact the Orange Empire Railway Museum in Perris, CA. Not only should they be able to answer your question, they may be located right next to the track route that you are referring to. They may also be able to suggest search locations based on where old stations or depots were located. You can contact them at the following:
Orange Empire Railway Museum
2201 S. "A" Street
Perris, CA 92570
http://www.oerm.org/
(951) 943-3020
Good luck and happy hunting,
Jerry Myers