I know I'm probably no help on this thread, but I couldn't find a good place to mount my adhesive disk so I have to use the suction cup mount for the windshield. Mine's a WorldNav Commercial Trucker's GPS & I use it between my PSD & my rig @ work. It doesn't have a problem mounting in my Sterling, but it does in my PSD. So not to hijack this thread, but if I can find a solid place to mount the disk, does a GPS necessarily have to be mounted near the windshield for a good signal?