Western Railcraft(?) made a reasonable replica of them. They are really a Johnstown, PA 35n series car(?) but were released in several color schemes, I believe that NOPSI was one of them. They were sold in three and two rail versions. Here is Johnstown 357 that I took a photo of at the Shoreline Trolley Museum back in 2007:
Not too different from NOPSI 850 (same place but in 2010):