I have made an offer on a 96 Cherokee with 2" lift spacer up front, aal rear and sye. 3.55 on 30X9.5. The vibe start at about 60 and goes up haven't had it over 75. It can be heard more than felt. Rides smooth up to 60mph not bad after that little hum from rear and vibe that would not keep me from doing 70mph if I am not damaging anything
I have been lurking but this is my first post so go easy.
What I understand from searching here is the harmonic vibe is more closely tied to driveline balance. Lower speed vibe is tied to driveline angle.