I fixed mine with small aluminum brackets securing the top and bottom parts together. It took a bit of fiddling to get it right as I had to bend each bracket to fit as nothing is straight up and down. If I remember I had to install 7 or 8 brackets in total.

I used some RTV silicone to seal things up as best as I could.

Since there is a known problem with water dripping onto the engine at cylinders 5 and 6, I took some aluminum duct tape and covered the screw holes on the plastic shield in case some water goes from the partition to the shield. There was evidence of water intrusion as the allen screws which secure the shield to the engine were all rusted out.

This was a very successful repair and the part is better than new as it will not crack again.