I'm interested in where you got this info? We do not re box anything unless the original packaging is damaged. For a long time Yukon would package other brands of gears in their boxes, I've even installed OE gears out of Yukon boxes, however they now only sell Yukon gears. This was on Randy's/Yukon, not ECGS. All parts we sell are authentic and from the manufacturer advertised. Now some axle kits may come in plain boxes, but that's because we purchase in bulk so we don't have the retail packaging.
You probably buy shafts by the crate since you sell pre-assembled axle assemblies.