E-Brake help please

I think were not talking about the same area of the strut.
On the right side of all the 11" brake struts in your first picture, the end with the spring on it...compare that to the same area on the 10" struts in your last pictures. THATS where the obvious difference is in the two pieces.
I know the end is bent over on both 10" and 11". The difference is HOW MUCH of the end is bent over. The 11" piece has a much larger part of the end bent over than the 10".