The normal plastic parts, C hubs, arms, steering knuckles, spurs. From the start instead of using that brace for the T4 bumper I use a hard T3 bumper. The T4 bumper doesn't touch the bulks and in a crash there's a chassis cracking issue. Most of the parts are going to take the hits and you'll wear them out before breaking. The only thing I broke was a front out drive from a really hard crash, so I would invest in some metal ones (SPR Nikita out drives) or the hudy ones. Also belts are good to have just incase.
The car is a tank!!!