I think it was the transmission but not totally sure. My father was driving the car from work as he had the oil changed and new rear shocks, and he heard a loud pop or noise from under the hood. It was enough for him to pull over and he said it sounded like a belt broke or something like that

Now when you drive the car you hear a roaring sound that increases with speed. And when you let off the gas to stop it gets louder. We have jacked up each side of the front wheels and when you spin them by hand you hear weird noises.

Doesn't sound good to me but has anyone had this experience and good give me direction?

I would suggest pulling the pan for a trans service that includes changing the fluid and filter. That should give you a good indication if it'* in the trans. Any metal is a bad sign.

My dad took it back to his shop and they pulled the pan and it had fresh metal in it. His friend, who is a GM Certified Tech and specialized in transmissions, is going to pull it out and go through it. And is going to replace the PCS while hes got it opened up.

Sucks but what can you do.

Only had the car for 2 months.

Sounds like the final drive took a digger...