I"ve had the tires balanced 3 times and front end checks out ok. It starts to shake at 58-60 mph. It'* a 96 se with magnasteer and 139,000 miles. I put the wheel off my freinds 96 on the right front of my car and it seemed to quit. Then i switched sides and it came back. Took the car last night and had the right front tire balanced and it was only .50 oz off. I watched the guy balance it and we look for any tire defects and didn't find on the outside of the tire. took it for a drive after having the balanced and it still shook. What gives ?

.5 oz usually isn't enough to be a problem. Try rotating your fronts to the rears and see if that helps (don't forget to put the rears on the front). If it helps, consider getting the tires road course balanced, and make sure the go up to 100 mph. Or consider buying new tires if the rotating/swapping moves the problem.

I have already rotated the tires, it got worse after that. What is road couse balanced ? Is it the same as being balanced on the car, were can i get it done and how much?

I'm guessing you have a tire severely out of round. A road course balancer will spin your tires at various road speeds and will bias the tires left and right like steering. It'* usually more expensive than typical spin balancing.

I had this done to my new tires in preparation for a run on the salt flats. They can find oddities in your tires much better this way. If your tires are under warranty, and they find an out of round condition, you should get free replacement.

Did you have your alignment checked? Sounds like you did, but just verifying.
Could also be a ply/belt seperation.

When I had the tire balanced last night, i stood there and watched the guy. The tire and rim spun true, no out of round rim or tire bulges. Could belt / ply seperation show only on the inside?

At the speed the tire is spinning on the balancing machine it won't show. It'* probably only in a small area and requires the speed with the weight of the vehicle loading it to the ground, thus applying more pressure to the affected area.
In other words, the slow (5-15mph) speed that the wheel is attaining on the balancer doesn't really give the best balance....as in exposing small ply/belt seperations under such conditions.

Hope you understand what I'm saying.

I had a tire that the belt inside came completely loose and would spin on it'* own inside the tire. The tire balanced fine, but at speed and weight the belt would shift.

I had a problem like this on my 96 K1500 Chevy. I rotated the tires and it was undrivable after 25 mph. One tire is our of round. I also had a strange bulge on one tire on my wife'* 99 Jimmy.... could have been a broken belt. I swapped it with the spare.

I had an issue with the cross car swapping that they commonly do now. Front d/* to back p/*...etc

Changing the rotation direction can cause issues when you are hard on the tires. (Did I just admit to being tough on tires?)

Sounds like Bill'* suggestion of road course testing should shake out belts etc being broken.