Normally, the case of the radio behind the rubber seal is slightly smaller dimensioned. You cut a hole for this size, insert the radio into it, then use either a mounting kit or, much less expensive, make your own.
Two bent pieces of aluminum or stainless (bent into the shape of an angle bracket, with holes in each end) serve the purpose very well. This bracket screws into the mounting holes on the side of the radio, and onto the back of the panel or bulkhead. You just have to position the holes for the radio correctly so that the bracket presses up against the rear of the panel or bulkhead.
Last edited by btrayfors; 12-10-2011 at 08:04 PM.