98 Box with bad vibration at speed

[dghii]

Currently in the process of working on a 98 Box with 117K miles I picked up last fall. The car runs and drives great around town but if I accelerate and drive about 65--75mph, the front end shakes to the point I will not go any faster. At 60mph and under it is fine.

The tires are older but have even wear. I know that at this age and mileage, all suspension pieces are suspect. I have no desire to completely redue the front suspension but am trying to figure out what is the most likely source of the vibration.

I have had the car on a lift (4 point, wheels were suspended) while I replace the motor mount. I pried around the ball joints with and examined pieces the best I could but found nothing of note.

With the car on the ground, pressing on the each quarter panel does not result in any noise or excessive rebound. Turing the wheels while stationary results in no noises.

I am wondering if strut bearing could be the culpret.

How else can I troubleshoot the front end and identify the offending part(s)?

Thanks!