Hi Alan,
Welcome to the site. "Your" truck is out there.... waiting for
you. A '66 long wheelbase wide box D100 shouldn't be too hard
to come by. From an aesthetic point, you could possibly open
up your search to include a mid-'65 and a '67 D100, as they
are very much like the '66. Put an ad in the Sale/Wanted section
of this site. You might also try this site....
www.sweptline.org
Happy Hunting!
John