I have a 1999 oldsmobile 88 , with a front-end shake @ about 55-60 mph car has 133,000 miles well taken care of , It is not a tire problem......we have replaced half shafts , left & right, hub bearings left & right, rotors , right front motor mount, left motor/trans mount, struts are fine ,ball joints are fine, control arm bushings are fine...We removed half shafts and plugged both sides of trans and no shake ,but that isnt under load either....ANY ideas ANYONE? ??? Im lost........

Welcome to the forum. To gain the most exposure for your issues you'll want to post in the correct section. For your car that would be "Other 3800 powered vehicles".

Have you had the wheels balanced?

Moved the thread.

OK, what you will need to do is jack up the front end, then grab the tire and try to move it from top/bottom and from left/right. Also try in/out and rotation. Watch the tie rod ends. If you see nothing, rotate the front tires to the rear and see if that changes anything. Other then that, try to have the tires spin balanced on the car.

Thanks Guys...Sorry I posted in wrong section....NOT a tire probem for sure...nor tie rods....Also with tire off and on jack stand @ 55 mph you can watch the boot on cv joint suck outward toward hub and expand and rubber hits bottom of strut...???????????

Have you had the alignment checked?

Yes alignment fine......This is a VIOLENT shake......Thanks.......

You checked all the motor mounts correct? I'm not sure how many your car has, I know you said you checked the right front and left one.

If there is no problem with the halfshafts disconnected (removed and holes plugged) it seems to me there must be something wrong with the shafts or CV joints.
Also check the engine and transmission mounts and have a look at the body structure like welds and front end to body connections..
Good Luck and I hope you do find the problem.