Vibrating Wheels

So I just had a 6in lift put on my truck, along with a set of 15x8 wheels with 33x12.5 tires. The lift was put on about 3 months before the tires and wheels were and during that time the truck was running fine. When I had the wheels and tires put on, the rear wheels are now wobbling. Not the front, just the rear ones are wobbling. I had the tires put on and balanced at a local shop, then I had a full alignment done at NTB a couple hours after.

When I noticed that they were wobbling I went to NTB to ask if they knew what it could be and they said that it could either be a balancing problem, driveshaft, etc, but it wasn't an alignment problem. But, I've kind of ruled out balancing as a problem because the tires wobble at all speeds, and I figured that bad balancing would only wobble at higher speeds.

I'll take any advice that I can get. I'm trying not drive it as much but it's my only vehicle, and I have to get to work somehow. I just don't want this to lead to future repairs that I can avoid. Thanks in advance!