I used one of the seat ribs to mount the ELT there is a hole in font of the ELT for the wire harness to pass through and have access to the face of the unit.
This rib already had a few hols drilled that line up with the base plate, I had to match drill one of the holes and up size them to accommodate the rivet size
I mounted the speaker further forward on the same rib so it was closer to the pilot position
The Antenna hasn't been mounted yet, I will update again with pictures of the completed install.