The Magellan Rail Car Dining Room (Source: Wikimedia Commons)
Many thanks to SWLing Post contributor, Ron H, who writes:
[Check out] the following link to a story about the communications car that was part of the Presidential train. [This] was originally posted on the Hammarlund listserve:
Click to access the_presidential_communications_railroad_car_crate.pdf
Thanks so much for the tip, Ron!