wouldnt wheel bearings give some sort of indication they were bad at lower speeds, a scratching sound or real dull bump feeling. Thing is absolutely smooth until I hit about 55 mph then it slowly starts shakin and increases in intensity, especially if you speed up at all. As you slow down the shaking will hang around till you get down to about 40 mph. Gets to the point where it is almost scary at higher speeds! Do you know of anywhere online where they have a parts diagram of the front suspension to a 1995 Suburban?
You won't hear bearings, or a bump cause they'll wear even. I'm not sure it would be bearings,,, but they are easy to check,, from the out side of the wheel, you grab with both hands (top of wheel) and pull back and push forward and repeat. till you either get a little knock or you get tired. If no noise, then that one is probly good. then go to other one.
I'm not a pro mech. There will be someone else that will come along and tell what the problem is. you just hang in there.
You said that the vibration was still exactly the same when you changed the tires, back to front.
I't just hit me,, If all your tires were baught at the same time,balanced by the same guy, you can jack up one front tire just to barely get it off the ground and spin it by hand and watch underneath. The gap from ground to tire should stay the same . If tire is not round, that would explain the vibration at higher speeds. Same for balance to. Tires can need a balance if their are a bit older.