The Southern cars have been done by N-Scale Kits.
http://www.nscalekits.co.uk/NSToFC.html I think I read they might be in "distracted mode" at the moment, but I don't know the current status. I have been wanting to place an order with them but have held off until I get an all-clear.
MTL did foobie schemes on their cars for NS, CNW, and CP Rail that I know of, and there could be Southern and/or other schemes too. There are/were a variety of CP Rail cars (that looked nothing like the MTL car) that are among the coolest TOFC cars ever made IMHO. One is being done by Rapido in HO at the moment (
https://rapidotrains.com/ho-scale/freight-car/canadian-piggyback-flatcar.html ) but I feel like the chance of them doing those (or much else freightcar-wise) in N is pretty low from what I'm hearing.
The CNW cars (and similar cars by MKT and others) are more-or-less straight "cutting the top off a boxcar" conversions. I hope to try one of the MKT's eventually, and I did buy the most recent MTL release of the ATSF car back in March. (one improvement with this run is they used white stirrups on the car instead black, just FYI) The MR article is from the December 1984 Model Railroader (I'm starting at it right now) and it includes an article about the cars, plus another article on building one in HO
from scratch!
