Rattle / Clank under bed

I have developed a clunk coming from somewhere underneath my truck / bed that is driving me insane. It rattles every time I drive over a crack, bump, pot hole, etc.

I have checked the bed bolts, they seem fine and bed is sturdy.

u-bolts and shackles are torqued to spec

does anyone have any idea what this could possibly be? It sounds like something is very loose but nothing moves under the truck.

VIDEO HERE:
https://streamable.com/4pjd32

 

Spare tire chain is zip tied up as well

 

Does it happen all the time? I think mine has some noise like that, but at an almost full tank. Maybe down to 3/4 of a tank.

 

Yes... nearly empty and still doing it

 

I am agreeing with checking the spare and chain. I guess you haven’t made any mods to the suspension.

 

Anything in your bed’s storage cubbies?

 

Nope

 

Muffler, exhaust pipe or heat shield?

 

Weird one for you to check- grab your rear shock bodies and try and rotate them side to side. I had the same issue- couldn't find it for the life of me. Turns out, the lower eyelet bushing on one of my shocks had cracked and expanded which was allowing the shock to rattle on the mounting bolt, making a awful clunk/rattle on any form of bump or uneven surface.

 

They both twist but no play other than that

 

Tailgate? Does the noise present itself when you take a speed bump with only one side of truck?

 

I pulled the tailgate off to eliminate that... seems like it comes from passenger side but I can't tell

 

Were you able to diagnose this without removing the shock?

 

This is driving me NUTS

 

I have the exact same thing ! I have been under the truck a zillion times checking anything and everything when ever somebody suggests something. I took everything out of the bed even the bed rail tie downs and everything under and behind the seats. NOTHING.
I tried going down by drive way hitting the breaks hard (not slamming them) to make it clunk to see if I figure out exactly where it is coming from but I can't. My wife and my grand daughter both have ridden in the back to see if they could tell - it seems like the passenger side according to them.

 

Yep! mine seems like it is passenger side as well. Are you on stock suspension?

 

Mine is definitely outside of the cab, so I am not even bothering looking inside

 

Yeah I have eliminated inside as well but that is where I started. Then I thought the skid plates then catalytic converter covers and on and on and on.
I have been under the truck so often my neighbor felt bad and came over with his creeper and told to hold on to it until I find what's doing it.

 

Is your rattle / clunk pretty much the exact same sound?

 

Grabbed my shock body and shook it around. Heard a clunk. Replaced shock and confirmed clunk was gone.