I agree with Roy, the 10-bolt is not worth spending the $$ on. Find a good 12-bolt and you will be much better off. Price for narrowing the housing varies greatly, from what I have seen. Usually if around $100.00 to $150.00, but BEWARE. This is best done with a jig of some sort, which includes a machined shaft, anchored by the carrier caps. This will ensure that the housing ends are welded back on true to the carrier. Otherwise, you will have problems with wheel bearings.