If you have your heart set on a t-maxx I would suggest upgrading all of the center chassis and leaving the a-arms plastic. It will break/bend so it's easier to change arms than a bent bulkhead. I would also suggest some sort of roll cage if it's your first truck as you will land upside down a few times and the engine is the highest point. The maxx will be a fun basher, just needs upgrades. If it's all metal it's just going to break like plastic so remember to give it a weak point that is easy and or cheap to replace.