Questions on the book references
 

Hello I am relitivly new to the army builder and i was wondering if someone could help me.

In the custom vehicle maker the rules for many of the upgrades say to refer to " CA2004 ", I was wondering what book/website this is, thanks.

You might get a more informative answer if you noted which game system you're asking about. Also note that there are specific forums for many of the game systems, and a question about one of those systems belongs in those forums.

Looks like the 40K vehicle design rules, and CA2004 would mean Chapter Approved 2004, an annual compendium that GW used to do for 40K. Generally out of print as of now.