Great explaination. We use the same thing on turbine engines. Like you said, every part has it own RPM, frequency etc. So it's pretty easy to nail down a bad bearing etc.
Someone ought to start a speadsheet on this vibration problem, What year models, what type tires, 2 wheel, 4 wheel, crew cab long bed or short bed, see if there is common bond.
My truck is 2015 2500 4 x 4 long 8 ft. bed 4 door Sierra and I have absolutely NO vibration what so ever. Best truck I've ever owned and I've had Fords, Chevy's and Dodges.