I've added some detailed instructions to my web page on installing a 7-pin trailer connector in the bed for 5th wheel and gooseneck towing on 2004 trucks. Includes pages from the Dodge wiring manual for reference.
http://www.klenger.net/dodge/7-pin-connector-installation/index.html
http://www.klenger.net/dodge/7-pin-connector-installation/index.html