So my GX is at 96k and I'm getting ready to do the timing belt/ water pump with new tensioner and pulley and coolant flush. I figured I would also replace the serpentine belt while it's apart. My question is whether I should also replace the tensioner and pulley for the serpentine belt, or whether its fine to just do the belt itself. Nothing squeaks or chirps. Are there any other repairs I should definitely do - thermostat?