Alright sorry for lying dormant on this topic for a bit. I work 12hr days so I’m a bit busy. I was not able to take a video of the wheels spinning but did have my dad drive the truck and take off with varying degrees of force to observe the wheel spin. Both rear tires spun continuously and at what appeared to be the same rate. My dad felt the skip/shutter as well so I know I’m not crazy. I did actually purchase 250lbs of sand and place that in the bed. 100 lbs over each axle and 50 lbs in the middle. I did notice a mild difference in the skip/shutter. However, it still remained. I’ve been trying to locate a shop in my area that I feel confident in its ability to diagnose the issue, but to no avail. None of the shops deal with in depth diagnosis of differentials or transmissions. South Main Auto (yea the one with the YouTube channel) is a 3hr drive from me and I was considering taking it there to have them take a look at it.Astro may be incorrect on this one. When traction control “kicks in” there is a noticeable decrease in engine output. The Toyota system will not keep the wheel just at the traction limit. It will cut power Aggressively to prevent loss of control
For troubleshooting only, I suggest trying some sandbags or concrete bags in the back of the bed and see if that improves things.