[longassname]

Trusting Tireirons info about the hub bearings to be correct I arranged to return the wrx axles without opening them and picked up another dif cover gasket from the dealership. It looks like the info about the SVX vlsd being superior to the wrx vlsd is most likely correct so I'm happy with the decision to use the svx vlsd. It obviously has MANY more plates than the wrx unit.

I installed the 3.7 ring gear onto the svx vlsd and installed it into the wrx case with the svx bearing retainers and shims. Since A and B were both zero for both cases this guaranteed the bearing pre-load would be correct and the backlash and contact pattern on the gears should also come out right. I used GM bright yellow gear matching compound to check and the contact pattern and backlash looked great. I didn't actually measure the backlash but you can get a good reading on backlash by where the contact pattern is and how it moves as you apply a load to the gear.

I installed the axles into the diff on my work bench and lifted the whole rear end assembly into place with a transmission jack.

There are no transmisison or engine error codes and it runs and drives without any issues. The car definitely feels different with the rear bias of the vtd.