Was not this train dieselized following the 1952 earthquake on Tehachipi Pass and a couple years later the GS came back on it north of Bakersfield for Espee diesel utilization purposes, the steam remaining until late 1956. Also, did one train, possibly the Owl, carry routinely a prison car at the head end for L.A. county inmates being sent to San Quentin?
The last couple of paragraphs give the date you are looking for on dieselization of the SAN JOAQUIN DAYLIGHT.
SAN JOAQUIN DAYLIGHT SP Trains 51-52 July 4, 1941 Los Angeles – Oakland daily each direction 478 miles 12 hours.
By Al
The SAN JOAQUIN DAYLIGHT was inaugurated between Los Angeles and Oakland Pier by way of the San Joaquin Valley and Tehachapi Pass on July 4, 1941. The new train sets painted in DAYLIGHT colors were actually comprised of two head end cars rebuilt from heavyweights by the SP Sacramento shops and repainted DAYLIGHT colors to match the rest of the train sets. All new Pullman Standard built coaches were assigned to the two train sets both articulated pairs and singles. The 40 seat Dining Car and Parlor Observations were from the original 1937 DAYLIGHT train sets. Each of the SAN JOAQUIN DAYLIGHT train sets were comprised of ten cars and for power the road initially assigned three P-10 class Pacific Locomotives 2383-2385 after semi streamlining them and repainting them in DAYLIGHT colors again at the Sacramento shops. A single Pacific was assigned as power between Oakland Pier and Bakersfield. A pair of those Pacific’s was assigned to power the SAN JOAQUIN DAYLIGHT between Los Angeles and Bakersfield. The helper P-10 that led the northbound SAN JOAQUIN DAYLIGHT from Los Angeles to Bakersfield returned as the helper on the southbound SAN JOAQUIN DAYLIGHT from Bakersfield. The inaugural runs were as follows.
Consist Departing Oakland Pier
2383 P-10 class 4-6-2 Streamlined Pacific Locomotive & Tender
5069 Heavyweight Modernized Baggage 30’ Railway Post Office Car
6091 Heavyweight Modernized Baggage Car
2492 44-Revenue Seat Coach
2478 Articulated 46-Revenue Seat Coach
2477 Articulated 46-Revenue Seat Coach
10200 40-Seat Dining Car
2480 Articulated 46-Revenue Seat Coach
2479 Articulated 46-Revenue Seat Coach
2487 44-Revenue Seat Coach