When i bought my 40 half-ton, it had two different fear fenders on it. Now i'm trying to figure out which one is correct. I'll try to explain as best as possble. I measured from the back mounting surface against the box, to the top of the wheel opening, in the center of the fender. Does this make any sense? One measured 15" and one 18" Is either one the correct fender? Thanks for any help. Jeff
