Whirling noise from rear of car when accelerating quickly

My 97 Tahoe just started making a metallic whirling noise from the rear when accelerating from a stop. I cant tell if it is coming from the rear gear box of from the drive shaft. I did lift the rear tires off the ground with jack stands and put it in gear and accelerated the wheels and was not able to hear the noise.

If I accelerate slowly and get it up to speed I do not hear the noise. It is only when I accelerate from a stop quickly that the noise starts. I have not had it over 30 since the noise started this morning. Will take it to a Transmission shop but would like to know if it is safe to drive and what I am getting into as far as repairs.