I've just started work on the MDC PS-2 covered hopper section of our web
site, by listing all the variations MDC is currently producing.
http://www.union.rpi.edu/railroad/images/rolling-stock/Kits/MDC-LO.html#LO

This was prompted by Richard's comments about Halliburton's not having any
PS-2's. If any of you scan the list and see a version where the road never
had a PS-2, that would save me a lot of looking. (It is so hard to make a
determination like that, to make sure on a big road you aren't missing
something. Especially where at this point there aren't any images for these
cars on the MDC site and so I can't go chase down car numbers.
(Yes, the model is clunky, but if the paint scheme itself is also not
proper, that's a double whammy.)
Thanks - John Nehrich