Southern Car & Foundry is producing a new kit for the ATSF Bx-12 extended height single sheathed boxcar. The kit is a one-piece urethane casting with all the details parts and decals. You only need to provide couplers, trucks and your time. Prototype were converted during WWII and the last one ran in revenue service in the early '70s.
You will be able to order direct from their website once the kit is posted.