1.The upgrade parts are made of 7075 aluminum, parts processed by CNC 3D machine tool are very precise, by adopting whole shaped technology, the products have the characteristic of high intensity and durability. 2. The front & rear gearboxes are the same, it fits for Savage XL / Savage FLUX Front/Rear Gearbox.  3. The 7075 Aluminum Front/Rear Bulkhead weighs 232.3 grams. 4. We have made the bearings bigger     19mm x 8mm x 6mm instead of 16mm x 8mm x 5mm