From 1967 through 1972,
low-back Mustang bucket seats were a special-order option
from Ford for F100 thru F350 trucks. These seats utilized
specially-designed mounting brackets which have been
extremely hard to find.
However, I was able to get
my hands on a full set of these brackets and hired a
professional CAD artist to create some detailed schematics
which could be used to fabricate these brackets for use in
your own truck. These images are shown below in either .jpg
format, as PDF files or as a .zip file which includes the
raw .dwg files which can be opened in AutoCAD or SolidWorks.