I need some help. I noticed today that under hard acceleration there is a strange clunk or rattle coming from somewhere under the truck. It's a 2013, 4.0, 4x4, double cab, automatic with around 75,000 miles. It's bone stock, no mods. I've seen a lot of stuff about driveshaft noise, but this is not a constant noise. I get the noise briefly when accelerating hard up to 40mph, and only on or after the initial downshift. After that, it seems normal. Any info at all would be appreciated. Thanks.