Hi Mike,
That bolt is a hex head on my truck. Looking at the FAM page Bill referenced above (sect. 11 sheet 19) both the lower and upper brace screws are listed part #443785. It looks to me that the lower one is drawn as a hex head so it follows that the upper one would be also. On the other hand, the upper one looks like it could be clutch head in the drawing.
How's my logic here? A lot of things have been changed on my truck, so no guarantees of originality.
Good for you though researching this small detail.
