That sounds about right. From memory there were 11 36' cars left in 1959, but having recently sold just about all their their PS1s to the Monon and I believe, the L&NE, I suppose the NYS&W had little other choice.
The operation looked quite interesting, involving a train consisting of an RS1, MP54 combine, one of the corrugated Budd coaches with a boxcar bringing up the rear. I think some NYS&W PS1s had brackets for marker lights for that reason. I do not know if the 36' cars did too.