Ya that drivline is maxed out in its operational angle. To much angle on both ujoints to cancel each other out. You need to lower it or alleviate the angles on the driveline. A cheap option would be to use a lengthened slip yoke from TT and use a rear drivline spacer. But that will not alleviate much from the driveline. It would be wise to invest in a toyota front driveshaft with rockrat adapters or a custom chev blazer double cardan driveshaft from Woody's, Six States, or a KAD drivehaft fom RRO.  If you daily drive it, dont get the KAD driveshaft.

You said you have a vibration around 3000RPM Does this mean in any gear? or only in 5th gear??

If in any gear then it's not driveline at all but engine.

The u-joints have to line up as stated earlier but the angles also have to be the same.

Put an angle guage on the 2 spacers (the flat) Both have to have the same angle to counteract the accel / decel of a standard ujoint.

With a 3 inch lift + a spring over I would think that it would be wise to have a new rear driveshaft made with a CV in the front and then turn your rear end nose up so the rear ujiont is nearly straight.
When you add a CV (stands for constant velocity) this will stop your drive shaft from accel/decel on each revolution. If you do this you have to straighten out the the ujoint in the rear

ok thanks guys! gotta save some money for a cv drive shaft! where the best place to get one? i want  to get a complete set up. shaft, adapters whatevers. just want a complete set up!

  As far as I have seen the yota driveshaft conversion is a diy project, not sold as as a just install version. Six states , Woody's, KAD drivelines along with other local vendors in your area make direct bolt in driveshafts for your vehicle. Though more money, less time fabricating or waiting and providing a quality product and confidence on or off the trail are some benefits. My 2 cents. Toy shafts are some what cheap and plentiful for this conversion, especially if converting to toy axles later. Custom shafts with american ujoints and spline and everything else are way easier to work on later down the road. Everything is cheaper for them and to me appear to be beefier.

well gonna check out my local driveline shop tomorrow... thanks for all help guys!!!!

If you can find it, the front drive shafts out of a 84 -85 yota are high angle drive lines, work great for the sammi's. 
I have a 2000 tacoma front drive line and im cusious to see if it works. 

Amilla

ok just ordered my rock rat adapters... toyota shafts here in hawaii are floating around like madd!!!! so its pretty easy to get! let you guys know how it goes!!!!! thanks!

Also, try a search for driveshaft at Ack's FAQ (link in signature...).  Links to articles with lots of useful information confirming and elaboating (pictures!) on the subjects covered in this thread.