Vibration at speed?

[DeerHunter]

Well I replaced the u-joints in the rear drive shaft this weekend and it made a big difference. The funny thing is that the old ones really didn't look bad and I couldn't feel any slack in them prior to changing them but with the new ones the shake or vibration doesn't start until about 70 or 72 mph and even then it is very slight. Probably about 10% of what I started with. I still have to replace the lower ball joint on the passenger side and then I will try to find somewhere to have the tires and wheels road force balanced and hopefully that should do it.
Thanks for the help and suggestions.
DeerHunter