I happened across a letter by Maxwell in the October 1973 NMRA Bulletin which has some differing dates. Here is the pertinent part of the letter.
From D&RGW Official Files, courtesy of Jackson Thode. In 1925, a 65' Turntable was installed. In 1929 a partition was installed between stalls 4 & 5 (counting from the river side). These 4 stalls were retired by AFE T-9905 in June 1944. The next reduction was made after October 56 as AFE 4387 was made to retire stalls 5, 6 & 7. The dismantiling was spread over a long period of time. Photo from June of 57 shows back walls of stalls 5, 6 and 7 still in place. No date on the turntable removal. Wish I had the June 73 issue to see if there were any photos or other pertinent information.