Anyone got a source for this? The rattling while driving, without it, is annoying. Local place doesn't sell one large enough, and the GM part number appears to be no good anymore. Anyone know if one can be purchased "off the shelf" from a large nut/bolt supplier? If I'm not mistaken, these are pretty thin washers comparatively, so a "thick" one may not work. I know I've got one around here somewhere, like I'll ever find it. Well, I will, as soon as I replace it.