That connector which goes to nowhere is for the A/C if you had it. I would check out the maintenance history on that truck as well, may be a little sketchy since you bought it off ebay, but i could be wrong. Try changing to 10/30 to eliminate the rattling. You realy don't need that much lift, you can easily get 3.5 - 4 inches of lift for around 300 bucks. 2 inch body lift, 1.5 inch ball joint spacers for up front, and 2 inch shackles for the rear.
Nice looking truck by the way...

93' Toy xCab
bobbed > 22rEB > w56 > stock duals > SAS > 4.88's > 37's