60 mph vibration

[Rod]

Took the 66 gto out for a drive today, when I reached 60 mph+ it developed a slight vibration and noise. I have new tires and wheels, also a new balanced driveline. Anybody have any ideas? Up to 60 it drives very smooth.

[G6T8O]

Can you feel if it's coming from the front or rear? Is it pos. you lost a balance weight on a wheel?

[bendgoatracer]

If you have a tremec trans in your car then the vibration is coming from overdrive. Pull the drive shaft and rear yoke off the rear axle and have the whole driveshaft balanced as a unit.
The overdrive triples the harmonics effect so all has to be perfect.

[Rod]

Thanks for the information I will try balancing the driveline and rear yoke together.