NEED HELP FAST VIBRATION PROBLEM?????

I JUST GOT A 1994 TOYOTA PICKUP.IT VIBRATES REALLY BAD AROUND 25 THEN WHEN YOU GO FASTER IT GOES AWAY.BUT WHEN YOU GET TO 70 IT VIBRATES LIKE NO THER REALLY BAD.ANY IDEAS
 
ALSO THE BACK IS 4 LINKED BUT HOW THEY DID IT WAS THE BOTTOM BARS GO TOWARDS THE BACK AND THE TOP BARS GO TO THE FRONT.IT SEEMS LIKE WHEN I LET OFF THE GAS THE REAREND SEEMS TO MOVE SIDEWAYS. CAN THAT HAPPEN.
 
ALSO IT SEEMS LIKE WHEN YOU GO INBETWEEN 35 AND 70 AND YOU LET  OFF THE GAS PEDDEL IT VIBRATES ALITTLE BUT WHEN YOU PRESS THE GAS IT GOES AWAY.
 
IM NOT FORSURE IF ITS THE DRIVESHAFT OR THE WHEELS
 
PLEASE GIVE ME YOUR OPIONIONS SO I KNOW WHERE TO START.ALSO SHOULD THE 4 LINK BE REDONE.
 
THANKS

Edited: 10/10/2009 11:20:52 PM by DOWNSUB

Sound like the drive shaft pinion angle is off and the u-joints are bad.  Can you post pic of the set up the would help

if it has a carrier bearing.. i would check that also. it could be that rubber is worn out,around the bearing.

Sounds like you have a 50/50 4 link. And if thats the case it would be wheel hop like a son of a bitch.

ya its a 50 50 and my friend sid thats why its feels like the rearend is on ice when you let off the gas.He also said pionion angle.so I will start from there.There is alot of rework to do to the truck. Thanks