2014 4 cylinder reg cab exhaust noise (?)

Greetings, I've owned two 2014 reg cab 4 cylindersl 4×4's, both have created the same noise that I always forget to ask dealership about, looking for insight ...
a rattling noise that seems to emit from just behind cab, sounds a bit like a can of coffee beans or dominoes. My ears want to say it's catalytic or exhaust as it only sounds when I lift accelerator at hiway speeds, compression related (?) Or, my other ear wonders if it drive shaft/u-joint/transfer case...
both had/have 2" lift.
Any thoughts greatly appreciated.

 

I was going to say check for pebbles in the cat shield as that made a rattling noise in my truck but was only audible at near idle unlike your case.

 

It was one of my 1st checks, even threw some rocks in one and banged on it by hand, but wasn't the trouble maker...
Thanks for the thought though...
I don't know much about exhaust, but it seems like it's created by the idle throttle, and resultant compression(?) Just at like 45 - 60 mph ...

 

I just got a rattle and determined that it’s the exhaust. I first noticed at take off and the rattle somewhat stops at highway speeds. I can make it rattle in park with a light throttle rev and it’s worse in reverse (not moving).

I took the driver side cat heat shield off and that didn’t help. With the engine off, I can bump the driver side cat or the exhaust pipe nearby with my hand and it rattles like crazy. cat appears to be rattling internally. I’m looking at replacing the y pipe with a URD mark 2 comp or u-spec (y pipe w/ cat back exhaust).

‘14 DBCSB TRD OR 4x4 w/ 200,000 miles