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Forgot what forum I was in. But the answer is the same. Get the manuals from erwin.audiusa.com for your vehicle and you'll have the info you require. A day pass is check for a car you're going to have for a while. On a US B9 S4, it looks like it'll be a type 0G2. Catalog page only shows one plug, N90281802, on the right side and a breather valve, 0AR525093A, on the rear top. Same config as the type 0D2, so if you find a reference for that rear diff, it'll be the same for the 0G2. Axle oil is G 055 190 A2.
Front differential oil G052145S2
Transfer case oil G055145A2
Rear differential oil G055190A2(I changed it at the dealer. This model can be confirmed) Information from the official search of Flowserve