Mark Morgan wrote:
"I searched the site for the Rail Road Progress company. How are there
c. 1970s-1980s "scratchbuilding projects in a box" consisting of
precut styrene sheet and strip along with Plastruct structural
shapes. Despite the lack of rivet detail, these built into
surprisingly decent models of their prototypes. These came out at a
time when the general consensus in the hobby was that "all hopper
cars looked the same", and the individual responsibile for these kits
also self published "Common Hopper Cars of the Northeast" which was
one of the first enthusiast works that showed that this was not the
case. Many of the Rail Road Progress kits have been superceded by
later models, but a few of them still are the only models available
for some prototypes.
See Jim Six's "Modeling Norfolk & Western's H10 coal hopper" in the
August and September 1989 issues of Model RailroaDing and
Teichmoeller's PRR hopper book for more information.