Still vibrating!

[waytoomanycars]

Just had a 2-Wheel alignment, balance and tire rotation on my F150 since I was vibrating my fillings out at different speeds on the highway.
Still vibrating in the pedal and the seat now when I brake or when I'm at 45 and 67 mph. Any ideas on if it's a brake issue, suspension issue or something else??? Couldnt' be something as simple as the brakes just wearing in a little?

[badass98svt]

If the seat is vibrating, it's usually a problem towards the rear

[bullitt5177]

Did you check your U-joints?

[mooch29]

Driveshaft out of balance? Sounds weird if it happens when you brake and only at those speeds though...does it happen when you are revving the truck up in neutral?