just a question... what truck are we talking about ?

normally the wiring is already there, since you won't find any assembly plant making a special underdash wiring for cars with deleted options. So I think you need just to get the lighter assembly ( sockets are pretty much universal fit http://cgi.ebay.com/ebaymotors/FORD-PICK...=item1c117f8267 ), fit on the right location and voila! wire will be there waiting for you

This wire ( on old cars ) is normally pink wire, sometimes with an splice for any other function with 90º barrel/bullet kind female terminal.

Sockets have a variety of disposition. The right one to make a nice plug and play job is a stud on back, but some of them are a prong, some other are wires with spade terminals.

The one I posted from ebay should it be the right one to make the plug and play job