Hazmatunit02

So as the title states, I’m having some issues. Noise is only happening when reaching a certain speed between 35-40(3rd to 4th) and when I let go of the gas. Manual tranny 100,000 miles 2014 JK. No idea if it’s the tranny or TC. Rear diff fluid was like tar, but idk if that’s the cause of the noise. Any suggestions are helpful. I posted a vid as well if it helps. Thanks in advance.

LC Boyer

Could be a bad universal joint, or a weak motor mount

Nitetrain

Engine tick or rattles ? Bad gas? Valves ticking?
If from the rear could be as simple as the heat shield over mufflers.