Most anytime you get a 60 MPH vibration plus or minus 5 MPH it's the tire balance.
Front U-joint can vibrate if it's going out, sometimes they do and sometimes they don't.
Overtorqued (or unequally torqued) lugs can cause a vibration, usually accompanied by that warped rotor feel when you apply the brakes.
I clean the rust from behind the front brake rotors (nd the drums) and put a light coat of grease on the hub where the rotors seat. Just as a why not kind of preventative measure.
I've picked up a balance vibration often when rotating my tires, they seem to wear into whichever axle they are on and swithcing the axle changes the balance.
I'm the only competant tire balancer I know. I take the extra time to break the tire off the rim, twist it and try it again if the wieght gets too high. I always spread my wieghts inside and outside the rim equally and use the smallest amount of wieght as possible. I even clean most of the thick junk off the inside of the rim before the balance.
It's real easy to toss a wieght, especially on the stock alloy Jeep rims, standard steel wheel type wieghts don't seat very well. Glue ons, are usually iffy anyway.
I once went nuts trying to balalnce a tire, finally figured out it was just one axle (right rear) and then discovered some bone head at the factory had put one retaining clip on a stud behind the drum. if the drums or rotors aren't sitting pretty close to flat, it will vibrate just like a balance problem often.