The heavytruck industry said goodbye and good riddance to 1990 as manufacturers closed the books with a 13 percent sales drop in December and a 16.6 percent sales loss for the year.

December marked the 16th consecutive month of double-digit decline in the industry with deliveries of 10,032 heavy trucks, according to preliminary U.S. retail sales figures from the Motor Vehicle Manufacturers Association.Truck makers also recorded their slowest quarter in four years. With just 120,951 units sold during 1990, it was the worst year since 1986 for heavy, or Class 8, trucks, defined by gross vehicle weight ratings over 33,000 pounds.

"There's been a tremendous loss of momentum going back quite a while," said Kenneth J. Kremar, director of capital goods and freight transportation at Economic Consulting & Planning Inc. in New York. "Certainly, the truck industry has been in a recession for a hell of a long time."

Declines in manufacturing, construction and capital goods markets have been more pronounced and more persistent than problems in the economy as a whole, reflected in gross national product figures that include the service sector, Kremar said.

While some recovery in the industry is seen as possible in the second half of this year if the Mideast crisis is resolved, Kremar is forecasting 1991 sales of 123,500 units or less.