Uleesis

I had consulted a Toyota mechanic in regards to the rough noise road coming from the front especially at low speed. He mentioned about the tires (with 35k miles) to be balance & rotated. The noise is still there but change slightly. Prior to the problem the front differential gear oil had been replaced (SAE 80W-90 GL-5) . I check the oil level and it is fine.
How can you check this trouble to detemined where the actual noise coming from?
Your respond & advised will be really appreciated..

Thanks
Ulyses Alfred Grant Lee