Final answer:
During drum brake servicing, the component that does not necessarily require axle replacement on both sides is the brake fluid, as it is a hydraulic, not mechanical, component.
Step-by-step explanation:
The component of drum brake servicing that does not require an axle replacement on both sides when being serviced is d) Brake fluid. Brake fluid is not a mechanical part but a hydraulic one; it does not wear out in the same manner as the mechanical components and can be serviced independently of axle conditions. In contrast, mechanical components such as brake shoes, brake drums, and wheel cylinders tend to wear out more uniformly and may require both sides to be replaced to ensure balanced braking operation.