1980 Ford L-Line 600-7000 Series Truck Sales Brochure. Ford! America's best-selling medium and heavy trucks. Popular LN-Series short conventional trucks...they're important reasons for Ford's continued sales leadership in the overall medium duty and heavy duty truck market combined. The LN-Series enjoy this popularity because Ford brings to this class of trucks many of the quality features that the biggest L-Line trucks have built their reputation upon. Chart gives specifications for LN-600, LN-700, LN-7000.