I commonly see posts from folks on trying to locate the source of vibrations. I had an issue with my '95 over the past six months that was a result of several things, not one in particular and figured I'd post what it took to correct.

I had done many different things to try and solve the prob, but found two particular things that fixed the prob.

Some of the stuff I had done...
multiple balance jobs
mic'd the tire runout
shaved tires
new tires
mic'd rim runout
replacement wheel
mic'd wheel bearing assembly
mic'd rotors
turned rotors
new rotors
wheels indexed

In the end, rotor replacement and tire indexing proved to be the solutions to the elusive vibration issue. I had tried all those things above, and one would think that after turning a rotor it would be true and straight, but alas, never assume. After re-inspection, rotors must have continued to warp to the extent that they tapped the shoes ever so slightly to cause the shakes at speed. Odd though, cause i never sensed pulsations during braking. Also, assuming that shaving or installing new tires (assuming that you have true rims) will correct tire runout was also a bad assumption. Turns out, indexing the tires with the wheels (aligning the tires highest runout point with the rims lowest runout point) was needed to resolve my vibration problems.

Anyways, figured I post what I learned... Just glad she is smooth like glass again.