Chris,
The difference between the two screws in 3/4 vs. 5/8 inch, easily interchanged, difficult to verify by a QA inspector after installation. A slotted hex head screw would have been easily accepted by an inspector as a deviation. However, both of those clips used a butterfly type retainer, not a screw. (You can see an assembled clip from AMK, 2014 Cat, pg 147, stock no - B-10276, Ford p/n 380374-S100, and page 146 for two better pictures of the butterfly clips.) What I found is the original butterfly clip had a sealer similar to the yellow 3M8001 adhesive in color, but with the consistency closed to a balloon, a very small balloon. Current reproductions use a foam disc, not like originals. AMK carries the butterfly clips, 352191-S8 (AMK 2014, pg164).
Jim