Cain,
I still use all the stock Durango ball cups and studs so I am unable to recommend a good 4.8mm ball stud. I read threw all these pages and the HPI ones come up because they are cheaper. I hear the Losi ones are good too. Make sure you get long enough ones for the rear hub if using plastic. You want the ball stud to go all the way through so you can put a nut on to keep from pulling out.