I'm looking at Cisco 3825 series routers.
I have found some but I can't find what the different lettering means for the model number:
Cisco 3825 Router (cisco3825v3pnk9)
Cisco 3825 Router (cisco3825dc)
Cisco 3825 Router (C3825VSECK9)
Cisco 3825 Security Bundle with Advanced Security IOS Software Router (cisco3825seck9)
Software Services included in the bundle, for instance all routers with k9 listed come with encryption enabled software. The one with SEC has security features and the 'V' I believe is for voice.
However the DC is very important, it comes with a DC power module instead of the regular AC power module so be aware of that model.
Please check this document:
Bundle means the router will come preloaded with an specific image for certain application and the related license, and/or certain hardware parts like DC power supply, DSP module for voice, etc. Consult your cisco reseller for more information.
Hope this helps, please rate post if it does!