RE: World Models Ultimate 40S
"I had two spare metal braces left over that I couldn't figure out where they were needed. I saw no reference to them in the manual."
On mine and in my manual, those braces go from near the top of the front supports to the bottom of the back supports. Holes were already drilled and bolts/nuts were supplied. From your picture, the holes are also in your front brace.
Let the rains stop soon, Glover