Now don't get all excited, I"m talking about my truck.

Has the highway shimmies right around 60-65. Smooths out over 70. Not horrible and you feel it and see it in the truck body, not the steering wheel. In fact, other than feeling it in your butt through the seat, it's the passenger seatback shaking back and forth that is really noticeable. Shakes side-to-side.

Shift lever (automatic) does not shake like the seat so it would appear that the shaking is happening all in the body structure. Can't even feel the shimmy in the lever.

New tires, new shocks, wheels true, new alignment, new rotors, new drums and no, repeat, no shimmy in the steering.

Driveshaft need to be balanced? (shouldn't I feel that in the shift lever?) Worn bushings in various places on rear end? Crusty U-Joints on driveshaft?

It's a 2wd 95 V6.

Here's some dancing poo just for fun:

 

Check and make sure the driveshaft is not loose.

My 93 shakes at this speed as well, and it ended up happening because I put a lift on and the angle of the driveshaft is not what it should be.

Also check the u-joints, and check/replace your transmission fluid.

 

Have who ever put your new tires on rebalance them.

Shakes at only a certain speed is usually a tire out of balance problem.

Shakes all the time is usually a driveline or steering problem.

 

I've had this problem with 2 sets of tires, one pretty new and the other brand new. Also had the first set rotated once with no change. However, I also thinks it is in the rotating stuff in the back, not the driveline. BTW, it is SPEED dependent, not RPM dependent, also pointing to the rear. Bearings? Diff?

Replaced the U-Joints in the driveshaft and that had no effect.

 

lift the front tires of the ground and inspect all the rod ends, pitman arm, and idler arm for play. my 4runner did the same thing at around the same speed turns out my idler arm was messed up.