96 S10-FrontEnd Vibration 2 wheel drive

I have a 96 S10 p/u 4cyl., standard shift.

I have a front end vibration at speed between 20-25 mph. The whole steering wheel shakes. Once past this speed + or -, it's fine.

I have had tire rotated and balanced 3x in the past month, no change.

Tires are Michelin's, still in very good shape, been checked, all ok.

I had wheel bearings checked, new cotter pins put in.

I just had a 4 wheel alignment done. Still no change.

What else could it be?

Thanks in advance,
Deb