Complete Modular Closing Wheel Hub. Comes in RH and LH configurations, the LH hubs have a "L" machined in end of stud. The LH has the reverse thread, RH is standard thread.
 
Key Features:
Uses heavy duty tapered roller bearings
Dawn standard 3-bolt hole pattern
 
Specifications:
Thread Size - 5/8"-18
Bolt Circle Diameter - 5 in
Bolt Hole Diameter - .53 in 
Hub Pilot Diameter - 2.80 in
Pattern - 3 Bolt