Elusive vibration starting 55 and continuing to highway speeds

[spyro235]

Originally Posted by SlickGT1

No vibration in steering at all?

Yea I would look at rear tension and control arms. As a matter of fact I’m here looking for torque specs for all the rear suspension stuff. About to go do this job.

The wheel does not vibrate back and forth on it’s own, no. But I do really think the vibration is driveline related, so I really think it could be my rear axles. They have a lot of linear play in them. Maybe I’ll try to source a used low mileage set.
I think it’s the driveline becaus a) my tires aren’t worn funny, and if it was a bushing flopping around usually the tires wear funny and b) when my rear end is squatting with tongue weight the vibration changes a bit. Squatting would put the axles in a slight different orientation, so it kind of makes sense in my head. I will be checking the fronts but my steering wheel doesn’t seem to vibrate. I can see the back of the passenger seat vibrating, and sometimes when it’s happening bad I can see the dash going up/down but I’m not sure if it’s the car or my seat vibrating me.