[Skyler]

I live in Southern Cali and have had to deal with the nightmare vibrations too. I would try putting about some weight ( 200-300lbs.) in the bed near the tailgate for about 3-4 months while you're breaking it in and see if it mellows out. I had some polymer shackles installed and it helped somewhat but a bit pricey @ $479.00, but a noticeable difference. IMO try the weight in the back first for a few 1k miles and I think you'll notice a difference.