The Putnam Division did not interchange with MN.
The Putnam Division was originally built as a new independent railroad in the 1880s, and was formally leased by the NYC in the early 1900s. It ran from a terminal adjacent to High Bridge in the Bronx called Sedgwick Ave.- originally it crossed the river on a swingbridge to terminate at 155th Street on Manhattan island. The line diverged from the Hudson Division right of way at BN tower, ran through central Westchester County, and connected with the Harlem Division at Putnam Junction, and terminated at Brewster. Traffic was local freight, some through traffic, some commuter traffic. Commuter trains ended in 1958, the line was tore up from East View to Lake Mahopac in 1962. The north end was largely abandoned by 1970, the lower half was slowly abandoned in 1975 (closing of the A&P warehouse in Elmsford), 1977 (no more service to Satuffer Chemical at Chauncey), and 1980 (no more service to Stella D'oro at Kingsbridge in the Bronx).
Check the New York Central forum for more info.
-otto-