Rear end rattle diagnosing?

[tsr2185]

91 k1500 350 700r4. With g80

I hear a loud rattling in the rear end when I brake or coasting off throttle at highway speeds, mostly exiting off highway. Sounds very similar to a paint rattle can. I stopped to fill up and check for play in the drive shaft but didn't notice play. I was also parked on a slight incline. Any thoughts on how to diagnose? I get home in a few hours and will be able to park it till its addressed. I never messed with a diff other than changing gear oil but I'm willing to try and Learn. I was initially thinking it was the rear brakes. But it does it without applying brakes as well.

 

[Caman96]

Exhaust, spare tire(mount brackets), something run over hung up under truck…? How do brakes feel?
Maybe take a real good look at u-bolts. I’ve seen some scary pictures of them and mostly you don’t see issue until removed.

 

[tsr2185]

Exhaust, spare tire(mount brackets), something run over hung up under truck…? How do brakes feel?

Everything feels fine. Maybe a little extra vibration at highway speed. ONLY does it off throttle coasting or braking at 70mph. And it's LOUD

 

[Caman96]

Everything feels fine. Maybe a little extra vibration at highway speed. ONLY does it off throttle coasting or braking at 70mph. And it's LOUD

See edit^^^

 

[tsr2185]

See edit^^^

Thanks I'll check all that out asap

 

[tsr2185]

Anyone cam share a video how to open up and properly inspect rear end? I feel like that's gonna be what imma have to do. Once I get under there

 

[Caman96]

Anyone cam share a video how to open up and properly inspect rear end? I feel like that's gonna be what imma have to do. Once I get under there

For the record, that’s not what I was talking about.

 

[RichLo]

Have you taken the drums off yet to check if theres a broken spring or backing plate rusted out or something obvious?

 

[Caman96]

Have you taken the drums off yet to check if theres a broken spring or backing plate rusted out or something obvious?

I did ask about function of his brakes, but he didn’t answer.

 

[Hipster]

or braking at 70mph. And it's LOUD

If it was in the diff you would be talking about howling, whining, whirring, clunking. A fallen apart brake adjuster, loose spring,a friction that's come loose from the backer, all will make a helluva racket. I'd check inside the drums first like these guys are telling you.