hello stovebolters of america! I need your help-I have some casting numbers and I need to identify what it is and what it came from?

top: GM n
casting # 22522678 also there is a k10 in the lower area below the casting number on the right side and on the left is this ....g25
5
A
on the very top is this D N with a circle or some type of round time mark?

any clues or web sites would be great. This rear has DIsc Brakes