I have a 86 pickup with 4cly and where my rear seal or bearing on my tranfercase to rear drive line has movement. My question is their a seal or bearing? Also it not my u joints.

 

It may just be a loose flange, it is very common. Look at the output shaft and nut while wiggling the flange. If the nut is loose get a seal and a nut, take off the flange, clean the flange, splines and washer. Silicone the splines and reassemble. Sorry I forget the torque and my FSM is out in the garage.

 

If its the bearing check you rear driveshaft, dents and knocks can throw it out of balance the vibration from out of balance will wear out the seal and eventually the bearing.