Front. Differential fluids should be changed and the proper additives should be used before installing axles on Subaru vehicles. Replacing fluids in the front, rear and especially center differential is recommended. Shuddering and noise are often attributed to axle shafts can be due to contaminated lubricants, worn suspension bushings or Ball JointsFirst Equipment Quality (FEQ) provides high quality under car auto parts, specifically for rubber and metal items, as well as front wheel drive axles