There were two different braces used;
metal brace fit under the top crown of the fender and attached to the fender with two rivets that can be seen from the outside of the fender. There was also
rear brace that secures rear of rear fender to frame rail. GM used one or the other through the forties but I'm not sure if both were used at the same time, I did for some extra stiffness. Hope that helps.
