Looking at the instructions I'm using the bracket should be at least 2 units downsized in height, taken off from the bottom cause the top (as seen in the picture in this thread) needs to stay at level with the white plate, that much is clear from the instructions.
But even with a two units downside it won't fit the beam, and a 4 unit downsize would make it even with the bottom brick behind it which is wrong (the instructions clearly show an overlap).
But even with a two units downside it won't fit the beam, and a 4 unit downsize would make it even with the bottom brick behind it which is wrong (the instructions clearly show an overlap).