Although the American Locomotive Company built the Southern Pacific's earlier Mountain (4-8-2) type engines, the last 49 were products of the SP's own Sacramento General Shops, erected between 1925 and 1930. The last one to be constructed was No. 4376 of class Mt-5. Many of these skyline-casinged 4-8-2s spent their final years in San Francisco commuter service, in which No. 4376 appears in a photo dated June 1956 from the collection of William D. Volkmer. For the dimensions of the Mt class consult the commentaries for No. 4315 and 4324 previous. None of these outstanding SP Mountain types have been preserved.