Well...it is a difficult fit to start with and then you have to deal with creasing the cardboard and the moving floating center bow(my 51). I used the water wetting suggestion and got somebody to help me the second time, but I still cut it a little short and put a small crease in it before I was done.
Most folks don't even notice to mistakes but frankly everytime I get in the truck, I see that darn crease...