Annoying Humvee Wheel Shake.......This may be your culpret.

I had a bad wheel shake when I drove over 30 mph and found it to be the pitman arm. After replacing the pitman arm, it fixed the side to side vibration.

[@Pilinchi1]

It's kinda hard to tell but I almost can see a movement between the bolt and the center link. Recheck, if it moves you may need to use a thin washer and it needs to be tight.

[@LHHomestead]

I had to sell the M998, I would have tried that trick tho.