My 04 Maxima vibrates when accelerating and the vibration has continued to get worse over the past couple of months. When you let off the gas, the vibration goes away. When driving at high speeds, it feels like the car is going to implode. I was told it could be an issue with the drivetrain or drive axle. I have also noticed a knocking noise in the front end/engine area when first accelerating, but not sure if the two are connected. Has anyone experienced this issue?? How expensive is a drivetrain/axle repair??