Try electrical tie wraps... this is a trick we use on the I-20... works great. Used by Rod Waterhouse, Micha Heemskerke, and various other long distance rock stars. Cheap, easy and tweakable... wrap around casting in 4 or 4 spots on both sides as well as the plastic washers John recommended. Don't squeeze the castings... castings to not deal well with it.

Jim Stone
Tybee Island
Pirates of the Tybeean Sailing Team