It's a 2 piece set. The base plate mounts to the bell housing. It made from 1/2" aluminum. The electronics plate attaches to the base plate with 4 rubber vibrations dampners. The base grabs the very top bolt of the block (it uses a spacer since the bell housing doesn't bolt to that hole) and the bell housing hole at about the 1 o'clock position.
Eddie

This is what I used to mount Holley ECU, relays etc. It bolts to the back of the starboard head, making a clean, factory looking install.

http://www.hardin-marine.com/p-13236...m-bracket.aspx

Steve