Clerk-
Car is a former Southern Pacific commute car, built around 1955, and used on the SP's San Franscisco Penninsula commute service between San Jose and San Franscisco (now operated by Caltrain). I do not know how many of these are still in service over the line, if any.
An outfit known as Bob Steele & Associates (BSA) purchased a large number of these cars in the late 1980's for $11,000 apiece. BSA operated a railcar repair facility that specialized in the creation of high class cars for "cruise" type trains all over North America, in addition to doing other work (such as producing bunk cars for Loram, the rail grinding railroad contractor). BSA's facility was located in a former blimp hangar just south of Tillamook, OR.
Sidenote that may be of interest- the US Navy built the blimp hangar in the early days of World War Two, and blimps based out of the base were used in coastal patrol and defense, primarily in guarding against attacks by Japanese submarines. After the war the Port of Tillamook Bay (a port district) was created to purchase the base and turn it into an industrial park. The three mile long US Navy railroad that connected the base with the Southern Pacific in Tillamook came with the purchase, and the port set up the Port of Tillamook Bay Railroad to operate the line. The POTB stayed a switching railroad until the late 1980's, when it gradually leased and then purchased the SP's Tillamook Branch from Tillamook to Banks, OR.
BSA re-built a number of these cars for various luxery tour operators, including Midnight Sun Tours (operating on the Alaska Railroad) and Transcisco Tours, which operated (for five months in late 1990/early 1991) an upscale cruise train between the Bay Area and Reno...the train was powered by a pair of FP45's and was painted a baudy red and blue. BSA also produced two of these cars for a sister company, Oregon Coastline Express, which operated (in 1989 and 1990) a tourist train service over the POTB between Tillamook and Wheeler, OR. The OCE used ex- Columbia & Cowlitz Alco C-415 switchers for power. (Another sidenote that may be of interest...the two C415's that OCE used were used again by Bob Steele & Associates on a second but equally unsuccessfull tourist train operation over the POTB, the Spirit of Oregon Dinner Train that used to operate over the eastern end of the line from Banks, OR. Following the demise of the Spirit of Oregon the two diesels and the train set were sold to the Mt. Hood Railroad of Hood River, OR, which continues to use the dinner train set today. However, the company had no use for the two C415's, and they were quickly re-sold to the Burlington Junction Railroad in Iowa).
This car appears to be one of the ex-Transcisco Tours cars...the ones that the OCE used had two more windows down the side of the car, and I don't see any evidence that they were plated over in your picture.
As for the Golden Sunset, it refers to the Golden Sunset Dinner Train, which is affiliated with the Sierra Railroad (which operates from Oakdale through Jamestown and Sonora to Ralph). The Golden Sunset and Sierra are affiliated companies, and the Yolo Shortline was very recently merged into the Sierra. I would suspect that car swaps like this may become common, especially if the Sierra is successfull in purchasing the California Western Railroad (operator of the famous Skunk trains between Fort Bragg and Willits, CA) out of bankruptcy. The judge will pick from amongst the four bidders in six days (the other three bidders are the Napa Valley Wine Train, another group of local investors out of Fort Bragg, and a group of investors out of southern Oregon).
Hope this helps and that I didn't bore you too much.
-JD Moore
Elko, NV