I guess I am still trying to see if my pup has GSD in him. His coat is overall pretty dark too but he also has that distinct black line/stripe on top of his back like you see in pure sable GSD pups when their coat gets lighter before their adult coats come in.Black stripe? Down the back? No. She had more like an all over black shading. Right now most of it is gone but her sire is colored like she was she was younger. Let me see if I can find a picture of him.