McDonnell Douglas Obtains Financing: McDonnell Douglas has obtained a $400-million credit line agreement, replacing an earlier one for $750 million that was to expire in December. The new agreement, provided by six banks, will extend over three years, significantly longer than the one-year agreement that preceded it. McDonnell Douglas officials said the new agreement is a significant vote of confidence in the firm's future by the banks, after downgrading in its credit ratings and cash-flow problems earlier this year. A company spokeswoman said the firm does not anticipate tapping the new credit line but will use it as a reserve. The banks are Chase Manhattan Bank, Morgan Guaranty, First Chicago, Citibank, Abn Amro N.V. and Bank of New York.