Last Steam on the Sunset Route

When did the last SP steam locos quit service on the Sunset Route?
On which part of the Sunset Route did the last steam actions take place?
When did the last SP steam vanish from Louisiana and Texas?
What types of SP steam were the last one´s to be in service on the Sunset Route?
I think it where the 4-8-4´s, 4-8-2´s, 4-10-2´s and 4-8-8-2´s, right?
How many steam locos have been needed to pull up a 20 to 25 car passenger train or a 150 car freight train up Beaumont Hill (California), Del Norte Pass (Texas), Chatedral Mountain/Mount Ord Pass (Texas) or over the Anacacho Mountains (Texas)?

As a starting point, I’d recommend Richard Percy’s Southern Pacific site, specifically his T&NO 1951 steam roster at http://espee.railfan.net/1951tnorost.html . I believe that most if not all steam was gone from T&NO within the following two years, beginning with the larger engines being transferred westward.

– Paul