This is how it's looked at Travel Town through the years:
You'll notice that it started life with what looks like a saddle tank and later it was converted over to those square sided tanks. All the "body work" is different as well, and the stack was changed to a straight one from that little diamond stack.
Was this the look it was given for the grand opening of Union Station in Los Angeles? That was in 1939 I think. At that event it was masquerading as steam-dummy #2 of the Cahuenga Valley Railway.
Here's a picture of what that little steam trolley line looked like around 1888. It was a narrow gauge setup, and SP #20 is standard gauge: