Not quite correct, Ms. SojournerThe operation of Sleeping Cars was divested from the car manufacturing concern by a Supreme Court decision United States v. Pullman Co.,50 F. Supp. 123 (E.D. Pa. 1943) 18 that bacame effective during 1947.
At that time a concern named The Pullman Company which was owned by the railroads and operated as a joint facility was formed. As you noted, operations ceased Dec 31, 1968, although the corporation was only dissolved during 1975 to enable various claims (labor matters, injuries, etc) to be adjudicated.
Amtrak never had any transactions whatever with the Pullman Company; the Superliner I's were built by Pullman Standard - their last passenger railcars.