Firstly.
Guys, please no more refferences to illigal street drifting. Would be nice if you maybe removed that from your post too guys
And back to the question.
I would consider that seems to be most shagged, if your diff is only spinning one wheel, then your still gonna find it a pig to drift with decent suspension in. however if your diff is still spinning two wheels then it is really your choice.
I would probably just put a diff ahead of suspension, but not by much. A very good and reasonably cheap suspension kit for a beginer is the whiteline kit (which just happens to be going for $2055 in a group buy with a years Membership to SAU-NSW included, $2k for members)
anyway... hope that helps a bit.
Dan.