You dont need anything else to drift with. You dont even need to lock the diffs. It will drift lovely out of the box with the drift tyres on.
Also i would not touch those 3 racing diffs,they are rubbish.
If you want ball diff's i would go for these below,they are good diffs for the price,tho they could do with a strip and clean before fitting as the factory grease they use is a bit too thick.
http://www.egrracing.com/shop/index.php?main_page=product_info&cPath=154_4_366&products_id=85
But if you want the best then the Kyosho ball diff is it,but they are around