Wrinkley boy

We didnt known what to expect besides pit. He's such a huge, lanky, wrinkley boy, I surely thought he'd have a larger breed in there somewhere. Guesses ranged from pit-mastiff, pit-dane, pit-boxer, pit hound, pit-sharpei. He's the runt from a litter that resulted from a white pitbull and some sort of brindle stray that was temporarily rescued and apparently got a little too comfortable lol. He's 7 months and 53lbs already and we think he's still growing. He looks so much different than our other dog, who is undoubtedly some pitbull variant. Those mixed genes are strong, especially the boxer/bulldog.