These ends are designed to fit Exactrail's Greenville 65ft Mill Gondola
They are used to convert that model into a BN 580400-580609 series gondola used to carry steel sections
The ends are pre-distressed to represent the beat up ends of the car, these cars originally had a wooden lining on the inside face of the end that was destroyed in service and in most cases not replaced. This wood lining can be added if desired and it appears to be made up of 2" x 6" planks. Pilot holes are provided for Tichy group bolts to represent the bolts used to hold the lining in place (photos on line show these bolts remained after the boards were lost).
Use Tichy Group grab irons. A vertical handrail needs to be made, .375 between legs.
For construction details see: http://www.hokitbasher.com/2015/09/bn-580400-580609-64ft-gondola-part-1.html