Unfortunately, the vast, vast majority of American pedigreed Shepherds are fucked up too. Most of them don't make it past 10, either. The ones I know are immediate descendents of European breeding stock.
Take this only as I'm saying it, your dog doesn't fit breed standards, he looks too wolfy.
Please do not misunderstand, that was
NOT meant to insult your dog! I am merely pointing out a potential reason he lived so long might have been because he was outside the breed standard.
This is a classically "good" German Shepherd, you can see there are differences (bear in mind, I'm talking strict confirmation and color standards for breed type):
Frankly, mutts are generally your best bet for health and temperament. Most pedigreed dogs (and cats) are physical and/or psychological messes due to the degree of inbreeding. You can't keep mating grandfather to granddaughter then uncle to niece and not expect to get some whack chromosomes sooner or later (an uncomfortable percentage of pedigreed animals have some inbreeding in their background, even if the paperwork doesn't show it, trust me, that crap is far too easy to fudge).