Abstract: A dock door assembly and a dock door assembly kit are provided for use in a dock door opening for installation in a warehouse. The dock door assembly comprises a pair of vertical tracks, with each vertical track configured to be attached to a wall along opposing lateral sides of the dock door opening. The dock door assembly also comprises a multiple, horizontal section door characterized by a vertical height when closed and mounted on the pair of vertical tracks. The dock door assembly further comprises a spring shaft assembly and a pair of headplates with each headplate having a U-shaped opening to receive each end of a torsion shaft. Further, the dock door assembly may comprise a pair of door cables and a pair of corner cable attachments connecting each door cable to the spring shaft assembly.