OK . . .
A little research and this is what I turned up:
Storage battery cars ran part-way up the Mineola-Hempstead Crossing line and down to West Hempstead. This line was known as the New York Bay Extension and later the West Hempstead branch.
The ex-Ocean electric trolley cars ran out to Salisbury between 1915 and 1933, when MP41s took over the job.
Electrification was completed between Valley Stream and Mineola in 1926 and at that time, scheduled MU service began.
Per Art Huneke's website, Employee timetable #104, effective 5/19/26 shows regularly scheduled MU service as train #s 940, 942, 944, 948, 952, 956, 958, 960, 962, 964 and 966 leaving Valley Stream and arriving at Mineola, 7.3 miles distant. They returned as odd-numbered trains.
Art mentions that a typical example of MU thru-service was train #958, leaving Flatbush Avenue at 4:27pm, hitting Valley Stream at 5:02 pm and arriving Mineola at 5:22 pm. This equipment returned as train #959, reversing direction and continuing back through West Hempstead, Valley Stream and on to Penn Station.
Quite substantial passenger thru-service!!!
Dave Keller