Diff fluid change, which gaskets

[hillstrubl]

I'm trying to change my differential fluid, was going to use Synthetic 75W-90 for both (Yes I know the front technically calls for dino 80W-90), but the question of diff cover gaskets has left me scratching my head. How would a 2011 Tahoe LT 4WD have multiple choices as per RockAuto? I get that a Silverado and Suburban had 2500 versions, etc but shouldn't a Tahoe be a single Axle config from the factory? I would guess its the 8.25/12 bolt axle in front and 8.625/10 bolt for the rear but I'm not sure...

Thoughts?