For what it be worth, during August 1964, the MP Texas Eagle #21 (yup, that was its #) departed Ft Worth 1055ACT and arrived El Paso 1115PMT, or 13'20".
By then, the Sleeper was adios; consist was a dome,coach, and Grill-Coach. There was likely still a hefty collection of Mail & Express cars. The connection onward to LA was with SP #39, a no-name coach only Mail & Express (the Golden State-Sunset was then "roundly" on its existing schedule)
"Downgraditis" had clearly set in.