Anybody wanna take a guess on this? Vibration is felt between about 65 and 85mph. It's a 6spd. I feel it in gear or if I pop it into neutral at those speeds. At the higher end of that mph range, if I pop it into neutral, the stick vibrates like crazy on top of feeling the car vibrate in the seat of my pants. Vibration does not change with rpm. Seems to be speed related since in neutral, the rpms drop way down even though i'm still cruising at the high speed. Driveshaft is a Denny's and is balanced. 12 bolt moser with 3:73's and a Spohn TA. Tires are new along with new ZR1's. I'd say tires are balanced, but can't be positive. No bent axles or pinion and gears are new. Anybody have input? Thanks.

Ken R.