Got new gears installed the other day.
And since the driveshaft was out, I wanted to get it balanced since the
vehicle started to vibrate at about 86 mph and then get worse from there.

Took the factory driveshaft to Driveshaft Specialists in Tampa.
The guy there, Dino, put new greaseable joints on, balanced the shaft at 3600 rpm and painted it. All for the low cost of $56 including tax.
There were two weights on the shaft from the factory. One monster weight and one smaller one. He pulled off the huge weight, left the smaller weight and put another small one at the opposite end of the driveshaft.
He did an awesome job and it's the best $56 I ever spent on my '94 Z.
The car is smooth as glass up to 105 mph, which is the fastest I've gone so far. Of course I only went that fast to test the balancing of the driveshaft!!

I highly recommend that anyone with the 80 mph+ vibration, get the driveshaft balanced.

 

Balanced LT1 DS > LS1 DS.

 

I'm going outside right now to put on my new adjustable torque arm, but I think I really know it's my driveshaft. I have a 72+ mph vibration. I bet you it's way more expensive than $56 where I live. You got a great deal. You could start a business painting/balancing driveshafts and subcontract all of work to them!

Ben T.

 

I replace my LT1 ds with an aluminum LS1 and right away felt a difference. It used to vibrate at around 80-85 and not with doesn't start until about 100-105. When I do my clutch I am going to have this one balanced and see how it works.