Decided to take some measurements and photographs. Click any image for larger size.
F0SZ-16A550-
A contains two splash guards. I have a set here in the original packaging. They are 13.5 inches (34.3 cm) tall at the peak, and 7.5 inches (19.05 cm) wide at the bottom. They're listed on the packaging as being for both the front and rear.
I also have a set of four I bought second-hand. Two match up perfectly with the above (the gap in the bottom-right one has been cut in by someone), while the two up top have a different shape both at the top (larger, more rounded) and obviously at the bottom. While I found an image for them on TCCOA, I have no idea what the part code on these top ones are, or what looks like precut ones in the picture below (if you know, please post). Both fit fine on the rear.

As an aside, I tried cleaning the bottom-left one right after I took this photo, because it had some rust stains on one side. I used CLR, thinking it would be safe, but it just stripped the paint off instantly. The bird etching is still there, though, so does anyone know a paint I could use to repaint the bird by hand, and that would hold up to the elements?
I also have two sets of E3SZ16A550-B, made for the 10th-generation Bird. As you can see, they are the exact same size as the 11th-gen flaps. So, if you like the look of the straight Bird logo, you may want to hunt down these instead.
10th-gen flap on left, with 11th-gen flap sitting on top of the other package to show how it lines up (precisely, curve and all).
Bonus round. I also have a set of F0SZ-16A550-
D. The packaging says "pliable rubber", but unlike -A they're more a plastic than a rubber--much firmer. Their packaging says they're specifically for the rears.
But while I was able to get -A to fit on the rears by drilling a few new holes in the rubber, these simply do not fit on my 97 due to the guard lip.

On the left is how they would need to sit if you wanted them to be aligned properly, and on the right is how they actually line up on a 97 Bird rear panel. So it looks like I'll be selling these.
Does anyone know what year the panel on the back would have changed? I'm guessing 96, but I don't know.