Rear diff troubles and hopeful solution

As mentioned before in a previous post that I was having issues with the rear diff on my Camaro. Well it is found out that the ring and pinion from another Camaro was wrong because it couldn't be setup properly. Then the other issue was the performance parts (Ring and pinion with Eaton Posi Diferential unit) that was ordered from Edmonton was wrong and long nights trying to setup the Ring and Pinion, then later found the Eaton Posi unit was defective. We found the right ring and pinion set from our local NAPA store and ordered a Detriot Truetrac Unit. Everything installed properly as it should.

I have experienced some vibration and gear noises. Feels like an unbalance in the driveline. I replaced u-joints and fixed the torque arm brackets. Still has vibrations and so on. I did some research on the Detroit Truetrac, it turns out you have to use regular gear oil, not synthetic. Because the unit designed to have friction to work. I have not put in this oil yet but I will give an update on whether it solved the problem and end the misery for those of us involved. 

Just to add that I think that I have found the partsman to count on in this city.