Clark Transmission 28000 Clutch question

Good morning, does anyone know what the clutch wear limits are for a Clark 28000 Transmission. I need to replace a few on one I am working on but wondered if I could save a few dollars if the others are reusable. The picture is of the discs that are in question. The brass fine thread ones. Thanks

Clark - Model :R28328-410
Serial : KUSA47268

Clark Transmission 28000 Clutch question