This is what I did to mount a 10 disk cd changer in mine
http://rides.webshots.com/photo/2355678610092261295BGYqCp
It's made out of aluminum, and also provides a storage space for a toolbox, spotlamp, and the factory jack mount (I had to get a bottle jack, original jack was missing). It's bolted to the floor on the sodes with 1/4-20 bolts, and is easy to take out if the tank needs to be accessed.

Bill Burmeister