Coveting a place among the top mortgage lenders in the U.S., Wachovia has bought its way into the top 10 with a largely unexpected $25.50 billion purchase of Golden West Financial, the quintessential mom-and-pop thrift that grew to become one of the biggest in the industry. Not including its acquisition of American Mortgage Network late in the year, Wachovia ranked 12th in total originations in 2005 with $57.71 billion, while Golden West (via its…