Need Cisco 4006 Switch IOS

I am needing the most current IOS for a Cisco 4006 switch. It is currently running CatOS 8.4(3)GLX, but wanting IOS. I think the latest version is 12.2(20), but would take anything some one has.

The management engine is Model WS-X4013
48 port swith models are WS-X4148-RJ

Any help would be greatly appreciated.