Early 3 and 2 seating into Grand Central Terminal

A few days ago, in the New York, New Haven, and Hartford forum, on the thread titled 1900s-1930s MU Fleet, Noel Weaver listed forty New Haven MU cars that had 3 and 2 seating, that is, motor cars 4070-4109, built 1926-1931. How early did 3 and 2 seating show up on the New York Central? I recall that the railroad bought 100 MU cars with 3 and 2 rattan seats in the post-war 1940's, but I have a faint recollection of 3 and 2 seating on Harlem Line MUs before then.
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Corrections, explanations would be welcome. Thank you. Joe

In New Haven in Color, Volume 2, page 15 is an interior shot labelled as New Haven BUT it is not New Haven but rather the interior of a 4300 class New York Central MU which dates back to the general period of the New Haven "Large Class MU's" meainng the late 20's or very early 30's. This car also had 3 and 2 seating and I believe all of the old New York Central MU cars from that period had 3 and 2 seating. The New York Central also had an older class of MU's which went to glory some years earlier than the 4300's and I suspect these particular cars probably had 2 and 2 seating. Having said all that, I still think 3 and 2 seating originated on the Long Island Rail Road sometime earlier.
Noel Weaver

In "Commuter Trains to Grand Central Terminal" by Tom Nelligan, Quadrant Press, 1986, page 24:
"The New York Central's original 180 MU cars of 1906-1907 were joined by an additional 186 vehicles between 1910 and 1929, as traffic growth demanded additional equipment. The majority of these later cars were 82-seat, 69'3" heavyweights built by the Standard Steel Car Company. This fleet of 366 first-generation MU's handed all electric zone local assignments through the 1930's and 1940's.
"The NYC began the replacement of its original electric cars in 1950, when it purchased 100 new 85-foot, 130-passenger MU's from the St. Louis Car Company. These were rather spartan machines, but they did bring the comforts of air conditioning to NYC commuters for the first time. Their longer length and 3-2 seating gave them a capacity sufficient to replace older cars on a two-for-three basis. An additional 87 cars of very similar design arrived from Pullman-Standard between 1962 and 1965, financed through the state and the Port Authority."
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I have been unable to find interior photos, but I can certainly recall riding the pre-war fleet in the 1940's and appreciating the new St Louis cars when they arrived in 1950. Our rides were mostly between Marble Hill and GCT, as Dad would sometimes give Mom a 26-trip ticket. I think the regular one-way fare was 35 cents in that era. On shopping trips, Mom certainly preferred the Central over the Interborough. For my part, I was dismayed that the Central did not allow the front-window experience the IRT offered.
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My plea to young railfans: Please take interior photos!
Thanks.
Joe McMahon

Good point. It's really hard to find interior shots. I suppose it's a matter of being present with a camera in a car that's empty or nearly so -- not easy to predict.