Was that noise there before you did the rear?

If there was no noise before then keep this in mind. When you change the pinion and ring gear they have to be set correctly for gear wear pattern, pinion bearing pre load.

It has been a long time since I did any rear end work so my memory is poor. I wish my dad was still here for he was the man to set up a rear. Though when you hear a noise when you apply the gas and or get a noise when you let up the gas and coast indicates that the rear was not set up correctly. Jeffrey