Train Masters were standard on Mayfield trains for the first few months after the run was dismalized, but Cadillacs and Geeps became more or less the preferred power. Someone once told me how they once witnessed an FM crap out and bottleneck half of downtown Los Gatos - blocking all those little side street crossings with a full train of galleries - as it slowly lurched back to Lenzen behind an ALCo switcher. Considering the first gallery didn't show up until the Louis Chess special in June of '57, that would likely place the date sometime in late '57/early '58. Also, Congress Junction (Saratoga Ave.) was renamed Champagne Fountain in '59, the year Paul Masson Cellars opened shop and the Los Gatos spur was abandoned. Not sure when Azule (Saratoga-Sunnyvale Rd.) was renamed Blue Hills, but I believe it definitely appeared that way on SP timetables by the mid/late '60s.

And as for big steam passenger power on the branch, the heaviest to my knowledge was a brief appearance by one of the semi-streamlined P10s (either 2487 or 2489 - or both) I have the exact date/details written down somewhere. I've also heard claims of a 4300 making the run, but nothing substantiated.

For a pictorial of the final steam and diesel commutes on the branch and further anecdotes, snag a copy of Images of Rail: Railroads of Los Gatos (Arcadia Publishing, 2006): http://www.amazon.com/Railroads-Los-Gatos-Images-Rail/dp/0738546615