try the haynes manuals..they usualy have the wiring diagrams in the back of them
try these guys also..they make the wiring diagrams easy to read..i bought one for my 66 bronco for 19.99 & it was so easy to read i fabricated my own harness from the diagram..you may have to email them to get your specific year..i told them i wanted a 77 bronco diagram for my 66 to upgrade from the old 6 volt & they had it but it wasnt listed in the site

http://www.classiccarwiring.com/ford.php