My shifter has recently started shaking when I get my car up to speed. I guess the most obvious diagnosis would be the need to replace tranny mounts. But I had a mechanic look over my car when I bought it about a year ago and he suggested that the car would soon need a new "selector shaft seal" I assume this is at the shifter but am not sure and the mechanic is no longer available. Could this be the cause of the excessive shaking, has anyone on this board ever had to replace such a seal? Any and all help appreciated, Thanks..