I have aluminum bulkeads on my T- Maxx. But my a- arms are still the nylon filled plastic. The plastice will flex under pressure, as where the aluminum will bend. Plactic $5.00 Aluminum $15.00. Just not practical. The impact is taken out in the plastic a- arms. If I had aluminum, the stress would be passed form the a- arms to the bulkheads. Possibly ruining both. But the aluminum bulkheads gives me more rigid frame for the trucks, allowing the weak points to flex with the plastic. Make sense?