These cars all appear to have nice large replacement 8' doors, reinforced drop side sills and lowered brake hardware. This definitely looks like a series of rebuilt cars from various original groups...
Indeed... and most of the mods to get the MT car up to snuff can be scratch built. Several great books out there you can reference including:
- Southern Railway Color Guide to Freight and Passenger Equipment
- Southern Railway Freight Equipment Diagram Book (Volumes 1,2, & 3)
- The Southern Railway Handbook
Lots of Southern Railway rivet counters out there, so get your calipers out...