Sheet #GS27-4012, date June 3, 1955. GS27- note is -ARR for (2) 68594?? cam devices. Front & Rear ... Rectifier Arranged.
The GS27 in this case refers to a Otis mod of AC controller with a DC overlay for a new retiring cam motor and cam motor- ?automatic gate closer? Also changed was a direct AC brake for DC brake and a DC brake control panel was added. Original Sheet #4012, date July 19, 1920.

Sheet #GS4-3329F, date April 16, 1954 (condensed? wiring diagram). GS4- note- Added Potential Switch.
The expanded wiring diagram GS4-3329F starts #3329D, date March ?, 1917,then #3329E March 26, 1917, then #3329F May 10, 1917. Ends #GS4-3329F, date April 16, 1954. Assume #3329 is the original sheet #.
As far as your question about the later number designations, Christy Collett, I don't know but started at least by 8-CIF6834A, date start 1,24,1949. final? Jan 16, 1953.