Not quite sure what you are after here.
If you are thinking someone switched gears on you. I pretty well doubt it. There is too little for anyone to gain by doing that and too much to loose. If you have that bad of a trust issue with a vendor. I'd say you should use a different vendor.
"More than you wanted to know" follows:
First, there are only so many actual manufacturers of gears. And they re-box each other's products and buy each other out on a regular basis. So the so-and-so gear is a problem - usually seems to fix itself and something else becomes the problem child every couple years.
I have seen "top of the line" gears have noise or breakage problems and "cheap gears" hold up just fine. The brand that works well in a Dana might not be the best in a Ford 9". This month.
A lot of it boils down to another case of Coke vs Pepsi.
Personally I don't care for Genuine Gear. I just don't like "the fit and finish" of them. And it always seems to take me longer to get a pattern I am happy with on them. But, a lot of people (ones who would know) really like them and I can't honestly say I have ever had a problem with them coming back for noise or breakage.
The ones I have seen the most consistant quality time after time. Are genuine Spicer gears and Precision Gears. And from what I am told by my biggest supplier they are made by the same people. I cannot verify this though, but they sure do LOOK like the same gear side by side. Have I had any better performance out of these. Than anything else? Not really.
Bottom line, if you got a name brand gear at a good price - you got a good deal. Period. The rest is up to the installer.