Clicking while turning right?

Okay, So my mechanic believes my differential is going bad. I get the "card in spokes" sound when turning right, and only right. It is a rythmic, rotational noise. Does it in neutral, or drive, or foreward or reverse. Can not duplicate sound on rack, Must have the load of the trans and car itself to click. Sounds exactly like half-shafts, but it is not. we just replaced both CV joints. When the wheel si turned completely left, I get a growling, grinding noise. I dont know if my torn Lower control arm bushing and slightly loose front left outer-tie rod have anything to do with it. And I dont know if the clikcing while turning right, and the Grinding and growling when wheel is locked fully left are conected. Car is a 99 olds intrigue with 3.8L and 4T65E M15 3.05 gears with 100k miles on it. I have the money for a full trans rebuild, My mechanic is NOT ripping me off, I work there as an intern and he knows what he is talking about. and A different company would do the rebuild anyway, so he wouldnt get paid. any ideas please? 3 ASE Master techs can not figure out what it is. Would anyone be able to give me the signs of a bad differential anyway?