Tacoma is shaking at highway speeds

Where are you feeling the vibration? Typically at speed is a balance problem. Road force is an absolute joke, it could still be the tires.

 

What I'm experiencing is identical to what OP describes. Cabin shaking left/right, most visibly seen by the passenger seat, but no vibration in the steering wheel.

I haven't really noticed the kind of rhythmic vibration people get with the needle bearing but I don't think that bearing would shake the entire cabin at 75 mph.
The truck had a 2" lift put on by the first owner so maybe the needle bearing does need to be replaced.

Another possibility I've considered is the drive shaft, but with only 7,000 miles?? I guess anything is possible.