Here are three more Missouri Pacific/Texas & Pacific blotters from Dale Hastin’s collection. The first has a 1947 calendar on it, which means it was probably printed in 1946.
This blotter is somewhat premature. The first Eagle streamliner was inaugurated in 1940, but as far as I can tell none used Texas & Pacific routes until 1948.
The Colorado Eagle began operating in 1942, so it is possible this blotter dates as early as that year. However, the lack of any patriotic message suggests that it post-dates the war.
The Texas Eagle was inaugurated on August 15, 1948, and replaced the Sunshine Special as the premiere train over both MP and T&P routes. The phrase “new streamliner” suggests this blotter probably dates from that year, but railroads often continued using the word “new” for several years after a train began operation.