Drive Line / Shaft imbalance question

[shimmersky]

I had my drive line replaced in early 2007 with a unit that tom svx helped me procure.
The original symptoms of failure were bad joints and an imbalance that caused a rumbling vibration at slow speeds and some strage stuff at super high speeds(over 100)
The replacement driveshaft came with zirc fittings that could be lubed as the stock unit does not??
The exact same symptoms are rearing their ugly head again.
THere seems to be an imbalance in the shaft causing vibration at slow speeds and the reconditioned shaft seems to be rusting in places after a bad paint job.
Just shy of 22000 miles on the reconditioned shaft??

Any advice on where to procure a good driveline??
Any place that sells these parts off the shelf???
Any ideas on the reason for these failures???