3.09 gear set with 3.23's

skep419 said
1st and 2nd gear there is Zero vibration all the way to 6500.

vibration happens in 3rd above say 3600-4000.

3.23 gears 100+ mph. Fixed

if you’ve got a driveshaft you want to send me that doesn’t vibrate I’ll gladly try it.

Tail shaft bushing, have you ever replaced it?
Is there a dent of any kind/size on the driveline?

The drums, have they weights or balance marks on them?

Is the vibration centralized to the firewall trans tunnel and do you feel the steering wheel vibrate when it occurs?

Is it in the rear of the car and does it pulsate?