I'm having trouble replacing Rear Brake Pads with anti-rattle clips OEM style.The clips came with Duralast max Brake Pads do not match.
If they don't match at all, then you need to find the right pads and clips.
If they simply don't fit, you may need to use a wire brush to clean the calipers. It is common for new brake pads to not fit at first. But cleaning the rust from the bracket should allow you to be able to get the new brake pads in.
Let us know how it goes. Post a picture if you of the old and new so that we can look at it and give you better advice.