This is a replacement drive shaft for an N Scale Bachmann 4-4-0 (older model with hexagonal nuts and large drive shaft).
This model has been designed for FUD & FXD materials. If printed in the FUD & FXD materials it will require cleaning before painting. I recommend washing with warm soapy water then soaking in 'Goo Gone' or a similar non-corrosive product for 24 hours. Then rinsing off with warm water and allowing to dry.
For more information please see my blog - www.jamestrainparts.wordpress.com