Use foam around your receiver. Everyone that stated the expanding stuff out of a can will not provide vibration insulation is absolutely correct. The owner of Radio South has told me that he wraps all of his receivers in at least an inch of foam because vibration is the worst enemy of a receiver. Do not tie them down so tightly that you crush the foam they are wrapped in. This will ruin the vibration insulating properties of the foam.
I always wrap my receivers in an inch of foam and hold them in place with a loosely wrapped piece of velcro, glued somewhere in the airplane. The velco will stop the foam wrapped receiver from sliding and will hold it in place.