SOUTHFIELD, Mich. (Feb. 2)—Global automotive aftermarket softening and falling new car production volumes continue to take their toll on Federal-Mogul Corp. The Southfield-based company took a loss of $337.7 million on net sales of $1.3 billion during the fourth quarter ended Dec. 31. That compares to net income of $60.2 million on sales of $1.6 billion in 1999´s comparable quarter. For the year, the seal maker took a loss of $281.5 million on sales of slightly more than $6 billion, compared to net income of $243.2 million in 1999 on sales of $6.5 billion. Two days prior to the firm´s earnings release, ratings agency Fitch IBCA downgraded the rating on Federal Mogul´s senior unsecured debt to "B-" from "BB-." The agency said the downgrade reflected a number of factors, including substantially weakened operating performance, the effective subordination of the unsecured debt to the recently secured bank debt which further weakened bondholders´ positions and ongoing asbestos liability concerns.