Shaking up and down vibration

I have a 2011 Toyota tundra I recently replaced the bearings in the front and the back because of shaking issues. They have gotten a little better but I’ve noticed a really hard vibration/shake at slow speeds that happens randomly and the truck will almost bounce up and down from the back/middle it is so random that I can’t pinpoint i. It seems very violently for like a short amount of time until I accelerate fast I have 163,000 miles. I’m thinking it might be the driveshaft or carrier bearing. I don’t know what else it would be

 

Had something similar recently with a Honda pilot. Under acceleration it was a mild vibration, but got really bad off throttle and even worse while slowing to a stop. Turned out to be one half of the rear u-joint froze up.

 

I'm leaning the same direction, had a similar issue with a Tacoma that turned out to be the carrier bearing.

 

Snowball,
My 2008 Tundra developed an up/down vibration in the mid 40 mph area.
Had lots of trouble figuring it out. Turned out to be a frozen right rear brake caliper (??).
Never understood the relationship between problem and symptom. Replaced caliper without replacing rotor and problem solved.
Retired ASE Master Tech and former Toyota T-Ten instructor.