The comment to use toilet bolts is, IMHO bad advice, much to strong. Now if you only want a removable wing, probably okay; but, most want the wing to shear in a crash. To do that use 8X32 or 10X32 nylon--yes 1/4X20 is much to strong. These are available in most hardware stores or from such suppliers as Micro Fasteners at very low prices. Even two 6X32 nylon bolts will hold any 60's wing on as they have a 50 Lb. tensile strength. I agree, that foam in a can has very poor vibration resistance and is not suitable for receiver padding.