Why aren't there any plans to use M9's for the SIRT which are being delivered to the LIRR. Since the SIRT is technically a railroad under FRA control, these cars would fit the bill perfectly. They could divert 35-40 cars for use there. In the 1970s when they were awaiting the R44s, LIRR MP72s were put into service.
SIRT is a stepchild of NYCTA and is isolated from the National Network,from the east end of Arlington yard to St George is torn up
and long gone. All rolling stock is barged to/from the Island.
They have new cars on order,and will be tweaked for use on SIRT as the R-46's were.