In need of extra power during the final Pacific theater surge of World War II, the Southern Pacific acquired ten 2-8-4s from the Boston & Maine, which was glad to part with its problematic "Limas," and converted them to burn oil. With their Coffin feedwater heaters the B&M engines were unattractive enough; when the SP removed the Coffins, painted the smokebox front and air pump shields aluminum, and fitted the engines with whaleback tenders they assumed an even more ungainly appearance. Nevertheless, photos reveal that the SP's B-1 class saw service on passenger trains as well as freight. No. 3506, the former B&M 4012, appears here at Los Angeles on April 15, 1950. The photographer is not specified, but the image was furnished by Carl Weber. For the specifications of these "Lima" 2-8-4s consult the commentaries for B&M Nos. 4016 and 4021 in this Random Steam Collection.