While I had the water pump out and the fan, I decided to take advantage of the situation and see how these damn accessory brackets are installed on the motor and where the bolts are hidden using the digital camera. Here is the pass side bracket that holds the A/C compressor. Looks like two on head and one on the bottom of the block. You can see the one on the head on the right side is a stud with a nut. These all looked like 9/16" to me.