thrdkilr,
The Cannonball continues in operation in 2004, although it isn't quite the same train as The Cannonball of the 1960s thru 1990s. On Friday afternoons only, May 28th thru September 3, 2004, The Cannonball departs Hunterspoint Ave at 4:06 PM, departs Jamaica at 4:25 PM, runs non-stop to Westhampton, arriving 5:41 PM and makes Southhampton, Bridgehampton, and Easthampton before arriving at Montauk at 6:48 PM. The Cannonball is identified by name in the Montauk Branch timetable. You have your choice of unreserved coach or "Hamptons Reserve Service."
Almost all of the Pullman heavyweight parlor cars used on The Cannonball (the all reserved parlor car only pre-1969 Cannonball consist pictured earlier in this thread) were retired after the 1968 summer season. The heavyweight parlor cars were replaced by a fascinating collection of sleeping cars, sleeper lounge cars, diner lounge cars, and tavern lounge observation cars acquired from B&O, FEC, KCS, NH, PRR and UP. These were designated LIRR class P80A, P80B, P80E, P80F and P80G; 2 of the cars were designated as business cars. Around 1975-1976, the LIRR retired almost all of these streamliner cars and replaced them with 12 of their own lightweight coaches rebuilt as parlor cars for "push/pull" operations; these 12 cars were known as The Sunrise Fleet and were designated LIRR class PP72. The Sunrise Fleet was retired when the new bilevel passenger cars were delivered. That brought about the end of true parlor car service, which was replaced by "Hamptons Reserve Service" -- much better than unreserved coach, but not quite the same as traditional parlor car service.
PERSONAL OPINION: If LIRR acquired/leased a group of lightweight passenger cars suitable for parlor car service (let's say 6 chair cars and 2 tavern lounge cars of Budd ancestry) and marketed it as traditional parlor car service, they could operate it at or near capacity.