Rattle

Have a slight rattle on acceleration, only when at low RPM, low speed and higher gear. Seems to rattle when I go to accelerate and the truck down shifts, then the rattle. It doesn’t feel like a slip or anything like that. No loss of power, no hesitation, nothing to indicate that something is wrong other that rattle. I have checked skid plate and heat shield, nothing is loose. Any ideas??

 

Drive shaft u joints.

 

It seems like it’s coming from under the hood but it’s hard to pin point it while driving. I’d rather it be a u joint than timing chain or tensioner.