I read the car number as NYC 859430. To my eye, the hopper in question
appears to be an USRA hopper rebuilt with panel sides, similar to the
panel sides once offered (still?) by Gould/Tichy Train. Although the
hopper appears to have the NYC system oval logo, the angle is such I
can't read the car lot number.

Can anyone offer any information about this car ? Am I correct about
this car ?

The number is probably 850430, which would make it a Lot 646H panel-
side rebuild in 1936 of "early standard" hoppers built by Standard Steel
Car in 1917 as CCC&StL 72700-73699(359H) and NYC 400500-401499(360H).
The rebuild included raising the sides to 10'8" so the USRA car would
work as a stand-in, although the panel shapes on the Tichy car (and the
forthcoming Accurail car) won't be exactly right.

The true USRA rebuilds were numbered 850100-850167(640H,1936); 850180-
850189(674H,1940); 850210-850299(641H,1936); 850300-850399(645H,1936);
851200-851299(655H,1937); and P&LE 37000-38418(651H,1937).

David Thompson