Remove the wheel covers if any and repeat your test, if the noise is still there then I suspect the noise is being caused by rust build up on the brake rotor brushing aginst the caliper or pads.

1. loose fender or flap?

2. U-joint (mentioned by Harry)

So many numbers

hmm ujoint?

I have a 1994 Ford F150 running a 5.0L 302. I'm hearing a ticking sound from the passenger side similar to an exhaust leak but its only present while driving down the highway >45mph. Its very subtle until I drive closely beside another vehicle or a barricade then it becomes very noticeable. The ticking is very consistent in tempo with the speed of the vehicle, not the revolution of the motor which is another reason Ive ruled out an exhaust leak. I've checked the wheels for foreign objects making contact. Heat shields have also been ruled out. I'm at a loss. Please help! Thank you.