This is also a trick. For those of you who have not been fortunate enough to meet Casey, with his height and arm length, he could reach the one on the right side from the left side of the truck.
That would be a neat trick, since there is a cap on the bed.
Casey, you're not giving us much to go on. Bite the bullet, clean the paint off, show us the markings from the casting, and then we can help. Oh, wait, by then you'll know for sure yourself!