2 things to do before you go crying wolf to the guy who installed the gears.
1st look under the car and see if the yellow dot on the D/S and the dot on the axle flange are lined up. If the are, try moving the D/S(try 180* 1st) and see if that helps. There are 8 holes on the flange so try all 8 of them and see if it helps.
2nd how many miles do you have on them? And did you take it easy for a while or did you just jump in and beat the pi$$ out of it when you picked her up! Not trying to be a dick, but if you didn't break them in you may have caused the whine yourself.
If none of the above applys to you then go back abd be civil with the guy and take him for a ride. If he's reputialbe, he'll take care of you.