The standard kit is B4 arms. I would suggest getting the upgrade from JConcepts for a new bulkhead, and heavy duty arms. I can look up a part number for you, or just go to JConcepts.net. The rear arms are fine. There needs to be a little bit of work done to the right rear, so it doesn't drag on the diff housing. The PLUS of that kit is that you can use stick packs from other cars (T4 or Touring cars, or what ever). The Worlds car just has more weight on the rear with the saddle packs. The Original is still a very good car. And handles well. JConcepts still supports that car, so no problem with parts. Really, just A arms in about all you will need. The drive train is tough.
JConcepts * Associated * Reedy