Last night on the way home from the track I noticed a vibration at 50 to 70 MPH. It just kind of comes and goes. It sounds like it may be coming from the rear of the car. If I give the car some gas the vibration stops, or if I let off the gas it fades away. Tonight I discovered I killed my factory posi unit, but I don't know if it could make the car shake that much. I have already checked around the car and I haven't noticed anything else.

So now that i know I need some new parts I am going to be ordering a torsen unit from SLP and would like to know what others think of it. Also what gears might be best behind a stock L98 and a 700R4 with a 2500 stall. Thanks.

 

If the problem is only at the speed you mentioned and has nothing to do with gear and rpm, then I would think you may just need the wheels re-balanced. But there could be other reasons for your prob.

The Torsen diff is worth the money. As for gears, do a search for opinions. I have a 3.42 but I also have a 5-speed.

 

If it only does it when there's no torque on the drive line in either direction, it's probably a bearing of some sort.

Replace the U-joints; if that doesn't cure it, check your pinion nut for being loose; if it is, you need pinion bearings.

 

Thanks for the advice guys I went out and rechecked everything, but it all looked good so I took the car out for a test drive. I noticed it stops when I tap the brake so I believe it to be the TCC lock up... either the clutch is bad, silenoid, or the valve is hanging up.