Today while crusing on the highway I went to put it into 6th at about 75 mph and the shifter started to shake alot and made noise. There is no problem with any other gear....

Anyone have any idea?

 

what gears you got? 3.42's? if so, i suppose youre at or a bit under 2k rpm? have you tried 5th at speeds under 2k rpm? does it do the same? if so, my guess would be plug wires

 

mine shakes at low rpms too, so its the wires?

 

broken tranny mount?

 

If jsut the shifter shakes, i wouldnt worry about it too much, unless it shakes a lot. My shifter shakes in almost every gear. Most likely the good old Gm factory tranny mount is old and mushy and wants to be upgradded to a poly mount. If the whole car shakes it probably plug wires as stated above.

 

Yeah now that I think about its probably the gearing...stupid question.