To my knowledge, the Southern never had green and white passenger equipment
matching the early passenger diesel scheme (but perhaps one should never
say never as there was a Southern gas electric which had a matching trailer
which may have been close). I think you have three general choices:
1) Heavyweight passenger cars in standard Pullman green. Walthers and
Branchline offer several cars lettered Southern that are correct or nearly
so. Bachmann also offers a Southern set, but these cars are mostly Pennsy
2) Heavyweight passenger cars in the two-tone green Crescent Limited scheme.
This scheme was introduced in 1929 for this one premier train, and was
disappearing by the early 1940's. The first E-6's arrived in 1941, and the
E-7's not until 1946, so if your locos are E-6's, it's possible a couple
unrepainted Crescent cars might appear in a consist, but if your locos are
E-7's, the Crescent colors would have been gone.
3) Most of the Southern's streamlined equipment was all stainless steel
fluted side cars. The models by IHC in the series with the baggage doors at
the very end of the car are correct or very close to Southern prototypes.
Some of the fluted cars by Walthers are also close.
4) The Southern modernized some of its older heavyweight cars (mostly
coaches) into streamlined appearing smooth side arch roof cars that still
rode on 6-wheel tracks. These cars were also painted Pullman green. To my
knowledge, no one makes a model of these cars, but you could make a stand-in
out of the Rivarossi smoothside coach with a new paint job and 6-wheel
Try going to the Walthers site and doing an advanced search for Southern HO