Vibration in '01 LS

I have an '01 LS Sport that just rolled over 80K. I just got home from a 1600 mile round trip with the car and it performed almost flawlessly. Got upwards of 25 mpg and did not feel like I'd been beaten when I got home; it was comfortable. The problem I had was an intermittent vibration strong enough to make the steering wheel shake. It was most noticable at 65 mph or higher. I just put new Michelin Pilot Sport A/S tires on it 2 weeks ago, so I'm sure tires aren't the problem. In fact, I replaced the tires because they were getting worn anyway and I thought they would cure the vibration. I have also thought maybe it was tired shocks and rough pavement, but it did not seem to matter what kind of pavement it was on. Also, it doesn't do it all the time. Other thoughts I've had are transmission, worn front end (I've checked that out and all seems to be normal there), something in the ignition causing a slight misfire, etc. etc. etc. I heard somewhere that drive shaft balancing is a problem with LS's some time too.

Anyone else had similar experiences?

o1 LS sport owner as well.have noticed a slight vibration in steering wheel as well especially at around 80-85 mph.had dealership check it out and found nothing,they say all is tight in front end components, so it must be something else.if you figure out the problem let me know

I would like to know if you hear a slight "drone" at highway speeds. The problem is in the rear axle shafts. The ford fix is a thicker drive axle not driveshaft. I've only know them to have a slight imbalance to cause a noise but a vibration is possible. The drive shaft has two rubber dampners(?) on each side and a hanger bearing, but it's probably the axles.

Thanks for the info, that makes sense. I'll get them checked out.

mine vibrated and went away after an alignment was done.