until I saw an ad for a model of this train, UI never knew it existed What can anyone tell me about it?
There's an account of it in Staufer's book New Haven Power and probably the NHRHTA Shoreliner maybe had a article on it.
Two conventional coaches (the power unit was probably a combine) were given rounded rooflines to mimic streamlining and one was fitted with an operating cab and fake Zephyr/Comet style end treatment...at one end. A truck was removed from the cab car and a special power truck with the Besler steam engine was fitted.
The Besler operated for several years into early 1940s almost always between Bridgeport and Waterbury. It was a one of a kind set (the NH had a number of one of a kind things in the roundhouse and on the road over the years) so during World War II, the cars were converted back to conventional locomotive hauled equipment.
If I can get up into my attic soon, I'll see if I can find an employee timetable or two. The Besler (along with the Comet, Shoreliners, Little Shoreliners and for a time gas-electrics) was shown when regularly assigned to particular trains.