Chris' Tips
Here is a drawing of the spindle that provides the overall dimensions.

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

Item No	Models
3	LittleMachineShop.com 4959 SIEG Mini Lathe - 7x14 (C3) Micro-Mark 82710 MicroLux Mini Lathe - 7x14 Various C3-US SIEG Mini Lathe - 7x14

Click your model to see the complete parts list.