Bad Boy 018-5006-00. 1/2-13 X 1-1/2 GR 5 Hex Bolt.

Use only if you have not purchased a new spindle or spindle shaft for this machine since 2008. The new spindle shaft requires a fine thread bolt which is part number 018-6019-00 (1/2-20 x 1-1/2 GR 5 Hex Bolt).