Yep, the humming noise I noticed but I thought it was the rattle noise you were talking about. Check for a rust-colored dust around the U joint which is sure sign the U joint is no good, you may need to remove the drive shaft to check it fully. Is the truck lifted? If so, then I would suspect the U joints, Also the noise can be the differential as well, remove the rear cover and look for metal shavings. These videos can help:
https://youtu.be/6F26Kir0OCg
And this is on a similar truck, but the procedure is the same.
https://youtu.be/p2snOCyqVMY
Please run down these guides and report back.
Saturday, September 3rd, 2022 AT 12:10 PM