cyclic vibration

[sellersrodshop]

i'm finally fixing to tackle some long needed work on my truck. the biggest concern is a "cyclic" vibration at cruising speeds. its weird, as it comes & goes in a consistent pattern & doesn't seem to change noticeably with speed changes. i'm going to check driveline angles tomorrow & see where those are at. I also put new tires on not too long ago but problem was the same with the old yokohama's so ruling out tire balance issues. best way I can describe it is a wet dog shaking. it starts out light, then gets heavier, then back to light & starts over again. any ideas??