Drivetrain Vibration

Drivetrain Vibration

What I did so far:

Balanced crankshaft (no vibrations in park - engine running smooth).

This made things a lot better ;)
But still vibrations while driving over 60.

Suspension (except leaf springs and high jackers) done.
New rear end (before 7 1/4, now 8 3/4 e-body rear).
Balanced driveshaft.
Aligned my 904 tranny.

No improvement.

New Toyo tires (instead of BF)

This was a slightly improvement but no game changer.

Symptoms:
Over 60 mph.
Sounds like: VROOM VROOM VROOM.
The faster you go the more intense it becomes (not faster).
Comes through the floor and the seats vibrate like massage seats.

What I am going to do next:

My tranny loses some oil, so this will be the next thing to look at closely.
I’ll keep you updated.

If somebody had tranny vibrations and fixed it, let me know...