Since the factory differential and ring gear are riveted together at the factory, when installing a Wavetrac differential or a new ring and pinion in your 020, 02A, 02J, 02Q or 02M transmission, you must drill out the rivets and replace them with special bolts and nuts. These are available from Volkswagen and also other aftermarket sources.After losing confidence with the quality and/or having been dumbfounded by the outrageous prices for these parts from these sources, we at Wavetrac.eu now offer what we know to be the highest quality bolt sets available for your differential installation. Produced for us by ARP, the world leader in high grade fasteners, our bolt kits are made from certified CHQ 8740 Chrome Moly material (rated well above aircraft quality). Threads are rolled after heat treat ensuring the finest threads that can be torqued more accurately without binding. The splines on our bolts are sized correctly for the crucial press-fit into the differential flange. We use ARP 12-point nuts rated at 180,000 psi or better. Bottom line: you won't find a better bolt set. You're buying the best differential available... now buy the best bolts to hold it!