A little history about these cars from a retired LIRR Conductor.
Cars 2709, 2722, and the revamped stainless steel car, were all originally LIRR MU's, designated as MP75's.
They were built in 1963 as the LIRR "Worlds Fair " cars.
The LIRR employees refered to them as "Zip Cars".
'They originally had dynamic break systems, where the older MU's did not.
They were originally meant to run seperately from other equipment, but after the fair, when the MU's were being fazed out, they ran coupled to other LIRR MU's.
Since they had dynamic break, and the other MU's did not, it was an adventure braking them while coupled to other LIRR Equipment.
In the late 60's, early 70's, it was a common sight to see an MU train made up of MP-75's, MP 54's, MP 72's, and the old double deckers all slashed together in a single train's consist.
Couple that with some of the cars still being Orange and grey with Dashing Dan, and others in the Blue and white MTA Colors, the RR ran some funky looking trains.
Here is a photo of one of the Zip cars on the East end of a Train in Jamaica, Yard D.
This was shortly before it was either scrapped, or converted to push pull use. They were originally numbered in the 2600 range, and later Re-numbered in the 2700 range as push pull cars.
Also notice how "diverse" the train is, on one train there are MP-75s, MP-54's, MP 72's in different colors..only thing missing was a double Decker. Also Notice the New M-1 next to it..It was a fun time to work for the RR.
(open Browser to large screen to see the entire Pictures)
Just for fun I added this Funky looking train..
Now about the 4th car in question, car number 2841.
This car is a T-72, an MU trailer, built in 1955 or 56. This was a MU car without an engineers control stand.
This car was NOT built in 1963 as the ad says.
The easiest was to ID these cars is the different style windows.
The MP 75 had long rectangular windows, The MP, andT-72's had smaller square windows.
All these cars apparently kept their last LIRR numbers.
Here is another MP-75 Converted to Push Pull service...These Images are copied from
http://www.trainweb.org/passengercars/Indices/L2.htm
mp-75, renumbered for Push-Pull.
T-72, in push pull service..
I didn't even see that meant the coach had its own system! Generator on the undercarrige.