Hello all, I can't find what GM 10 bolt rear end I have. Please see picture. I got it from Spirit Industries and they told me a 1990-1994 S10 Blazer. When it arrived, there were no backing plates on it. I bought some from a junk yard but when I bolt the wheel cylinders in them, they won't bolt up to the rear end. I can't find the casting numbers - tried that first. Anyone out there to help me?