I had the same problem. You dont need to use the mounting bracket.
What I did was to mount it directly to the tray. I carefully drilled new holes to line up with the CB mounting holes. Then at a hardware store I got (countersink) screws that match the threads on the mounting holes in the CB and a bunch of washers to act as spacers. Finally, I mounted the CB with two mounting screws each side. It worked great. You have to use countersink screws because there is little room for clearance. It is easy - just be careful to line up the screws in the correct spot and to make sure the CB is far enough back in the tray to clear the front of the console. You may also have to trim away part of the back of the tray if you have a big CB like I do.