The U.S. mortgage market became increasingly diverse in product mix through the third quarter of 2004, as the so-called non-conforming sector grew to overshadow the part of the business that fits through agency purchase windows. According to a new market analysis and ranking by Inside Mortgage Finance, the combined market share of the conventional conforming and FHA/VA sectors for the first nine months of the year totaled just 48.1 percent. That’s a major change since…