Credit Suisse First Boston is also leading a credit to finance the sale of Great Lakes Dredge Dock Corp. to private equity firm Madison Dearborn Partners for $340 million. Lehman Brothers is the joint lead arranger on the deal. Venture Holding Co., a portfolio company of Citigroup Venture Capital, is the current majority-owner of Great Lakes. Calls to Madison Dearborn and Great Lakes officials were not returned.