The prototype locomotive's history, as far as I could piece together:
From the CPRR Discussion Group: "What we know (or think we know) is as follows.... Vulcan produced three 2-2-0 locomotives to Charles W. Stevens designs. The first was delivered to the San Francisco & Oakland RR. The other two were subsequently delivered as kits to the San Francisco & Alameda shops and assembled by Andrew J. Stevens (younger brother of C. W.). By the mid 1860s both the SF&O and the SF&A were under common ownership of Alfred Cohen, with A. J. Stevens as Master Mechanic, and later General Manager. By the end of the 1860s Cohen was in the process of selling his lines to the owners of the Central Pacific, and was acquiring larger 4-4-0 locos (both home built and from Schenectady). Two of the three Vulcan 2-2-0s were sold ? we suspect the two SF&A engines. The remaining one (we think the SF&O engine) remained as the Oakland switcher and was scrapped by the SP in the early 1870s (although there is one source suggesting this scrapped engine might have actually been a steam car originally from the Market Street RR).
Anyway, one of the sold 2-2-0s went to the Los Angeles and San Pedro as the "San Gabriel". The other was sold to the San Rafael & San Quintin..... "
John H White Jr. lists the build date as 1864 (in his book on American built Singles), and I read somewhere but can't find it (probably on the CPRR Group page), that the drivers on these were about 60" with 9x18 cylinders. Allegedly it was too light for the SF&A, so the LA&SP got it in 1868 and used it to build the line - I haven't found any reference to exactly when it was scrapped. And the one photo shown is the only one I've ever seen.
This photo is of a sister engine sold to the Vaca Valley Railroad, and named 'Vacaville' (prior to the 1870 names were more common than numbers for US locomotives)
From what I can tell, there were a total of 6 or so Vulcan 2-2-0 locomotives manufactured before they went bankrupt. 3 were 2-2-0 with tenders the rest were assembled with (Henry Casebolt?) coach bodies as 2-2-4 steam cars.
At least one of those, the 'Calistoga' was later converted into a 2-2-0 with tender in 1875.