let's see what they say, but don't commit to anything just yet... a noise that has to do with a Plastic-like" sound is not a differential problem for sure.
You might try to inspect your wheel wells for scuffing or rubbing marks caused by your tires; the rubber boots of both drive axles and rack & pinion. and the tie rod ends.
*if steering knuckle is the prob... some greasing should lessen the sound somewhat, if not eliminate it; unless it is obvious that your tire moves untowardly when u manually shake the tire from side-to-side by hand.
__________________ ay sino caddi ububblaem?   Heaven won't take me; and Hell just knows I'll take over...! | 
