I am working on a 3RS train to go with my Atlas Southern GP35 that was converted to 3RS. What I need is a Southern Railway caboose to end the train.
Larry.
You could go with the Atlas bay window Southern caboose, No. 0737 in 3 rail and 0787 in 2 rail.
If it is too easy to get an Atlas caboose to go with your Atlas geep there are other options.
K-Line made the K-612-2012 Southern bay window caboose.
Lionel used the same tooling for the K-Line by Lionel 6-22282 caboose.
Lionel used their own very nice Standard O tooling for the 6-17663 caboose from 2004 Volune 2. It has roller bearing trucks with rotating caps.
MTH has made several scale Southern bay window cabooses in Rail King and Premier. The 20-91045 goes back to 2001.
The 30-77113 appeared in 2006 volume 2.
And the 30-77210 was in 2012 Volume 2. It shipped less than a year ago and several shops show it in stock on the MTH product locator.
There are plenty of O scale trains out there. Sometimes it takes using the manufacturers search feature to find out what has been made. Once you know what to look for it shouldn't take too long to find a car that meets your needs.