SEO Crawlability
 

I visited SEO Crawlability site they claim that vBullitins archive section does a good job but NOT good enough since the search engine sees duplicate pages when crawing the regular section and archive section. Save your customers some money and create a simple mod to redirect search engine to the archive section base on search engine ip address. Once you create this mod you do not need to zend encrypt it with license and give it away for free instead of charging $150.

there is an option available in your admincp (stock vbulletin code) to re-direct archive content to appropriate showthread URLs..

I am using 3.0.17, it does not have that option. Not sure if I should use mod rewite rule or just simple header output. I need to research further on php.net or some other author sites which is helpful.