I remember taking the train from Providence to NYC during the mid-1970’s. True, Amtrak never owned any of the older Pullman Bradleys, but Amtrak was able to play mix and match not only using their own equipment, but also Penn Central rolling stock. Many of those were ribbed-side ex NYC sleepers converted to coaches.
that ended when the Heritage equipment was sidelined and replaced by Amfleet cars.