The white ball cups are made by Losi, RPM and JConcepts but they don't fit the metric Tamiya ball studs so you need to get some HotBodies ones. They do two lengths and you need a pack of both to do the car. If you do a forum search there is a post with the part numbers for both packs
I use Jconcepts cups but the they're a bit short for the standard rods. RPM do long and short shank cups so they would probably be the best bet.