vibrations

89 cherokee nv4500trans. I had bad vibrations and my rear ujoint was shot. I replaced it and inspected and greased the other ones which was about a month or so ago. Now um getting vibrations again. I happens in 5th gear. I put it in 4th same speed it goes away. Then sometimes there is no vibrations it runs smooth as butter in 5th. What is the next step? i go to silver lake in a month. Or should i even worry?

anyone?

have you rechecked the joint you replaced and the ones you lubed?

do you have a SYE and do you have a lift?

is the pinion angle currect for the type of driveline you have.

have you checked the transmount for play?

check bolts check joints, sye is tight 6inch lift, havent checked the transmount didnt think of that