The State Belt Railroad Of California (later San Francisco Belt Railroad) received 6 new
ALCO S-2 between 1943-1945 numbered #20-#25.

Two of them survive today in San Francisco.
#23 as backup for the San Francisco Bay Railroad.
#25 sidelined waiting for future museum or display use.

Since I see them long time ago I always thought the black paint with yellow stripes was
the original paint scheme.

Now I come across this builder photo on the internet. Looks like the factory paint was
completely different.

Did anybody know the colors of this paint scheme?

Found a model railroad video on youtube:

https://m.youtube.com/watch?v=AfdP_s8xWmk

Here they run the ALCO's almost in the above paint scheme.
No fancy colors only painted black and white.
Any guess if this is prototypical correct?

Page 121 of the book, "The State Belt: San Francisco's Waterfront Railroad" by Kaufman and Kaufman, states:

"Order S-1892 from Alco arrived in the summer of 1943. This was numbers 20 and 21 painted up in black and white. It was a very simple livery as befitted a wartime effort. the trucks were black, the roof was black, the top of the hood was black, and there was a black stripe along the side lettered for the "State Belt Railroad of California" on two lines. The number on the side of the cab was black as was the diagonal striping on the front of the hood. The lettering and everything else was white."

And:

"Order number S-1885, engines number 22 and 23, was shipped out of Alco in March of 1944. For these the black paint stripe continued on around the cab and the number was white."

Brian,
thank you very much.