Can you buy the factory system and install it after the fact?

Look for Myron and Davis system.
http://www.myronanddavis.com/products_detail.asp?ID=134&LineID=12

Looked where are the prices?

Looked where are the prices?
That's the M&D website, no price. You would have to find a retail dealer for price. I just posted that site for FSUMich to get an idea of what he's looking at. Check with ETruckOutfitters for price.
http://clubtitan.org/forum40.html