JBL subwoofer rattle fix

I have had my '08 doublecab since November of '07. The truck came with the JBL sound option so I was looking foward to having a little bass. However when i would turn the volume to about 30 I would get a rattle from the back that you could hear even outside the truck. I folded the seats down and removed the four bolts that hold the plastic liner to the interior of the truck and slowly worked the plastic liner off revealing the sub and amp.

With the stero on I noticed that the rattle was coming from the upper left corner of the black plastic peice the amp and sub are mounted to. I also noticed that there is a mouting bolt missing in that spot.

I was able to get a small rubber grommet between the metal of the cab and the plastic mount for the amp and sub, problem solved. So has anyone elso noticed this as well on theirs?

-Dan