The Southern had a bunch of modified 3-bay open hoppers for clay service.  These are the ones with sorta-clamshell doors held closed by chains that were wrapped around spools on the carside.  I gather they mostly were used in the Carolinas.

My question is what customers did they serve?  Were they just for clay or did they also haul wet phosphate rock?  Have they been covered in TIES?

Thanks!  Hope to see some of you on Friday at the Archives.