Spindle, X3 Mill 

Chris' Tips
Here is a drawing of the X3 spindle.

In your instruction manual, this part appears on the parts list as:

Item No	Models
7	Grizzly G0463 Grizzly Small Mill Harbor Freight 93885 Central Machinery Small Mill Various X3-US SIEG Small Mill Woodstock International M1110 Shop Fox Small Mill

Click your model to see the complete parts list.