If i was you i wouldnt use the BC or IB5 you will still be on a time bomb in some ways, check the diff see if its a ATB diff or just an LSD from an RS turbo, you can get some good/better boxs for around 1500 with bigger bearings, new IB5 cases and quaife ATB and treated gear set, the cool thing is now the quaife ATB is lifetime warranty !