Noise from rear end suspension or loose truck bed?

[Nu2SDF350]

Thanks for the tips, all. I will investigate those this week. Here is video if it helps narrow down the issue. It only takes very minimal rocking to make the noise. You can do it by just using your fingers.

If all you're doing as lightly pressing the spare tire to re-create that noise, check the tire mounting? I can see the tire moving as you are pressing. It can't hurt to rule that out.