If it hasn't been destroyed, there's a concrete substation building at Valdez on the right-of-way of SN's Holland Branch (below West Sacramento). Cast into the front wall were the words, "Sacramento Northern Railway Automatic Sub-station." Inside (at least in the 1980s) was all the electrical equipment, thoroughly trashed and vandalized. I haven't been to look at it in many years, however.
About twenty years ago, I saw two substation structures on the Visalia Electric (or whatever a substation is called on an AC-powered railroad); one was between Visalia and Farmersville (actually on the SP where the VE had trackage rights), the other was in Woodlake. Still there?