Despite denials that a replacement for the 757 was in its future, Boeing Co. (NYSE: BA) has been showing some customers a concept aircraft dubbed the 737-8ERX, a long-range version of the company’s forthcoming 737-8 MAX. Like its predecessor, the 737-8ERX is designed to fly so-called long-thin routes, with fewer passengers traveling longer distances than the single-aisle 737. The concept is Boeing’s answer to the A321LR, which rival Airbus announced in January.

The first 757 was delivered in 1982, the last in 2005, and the single-aisle, twin-engine plane sold 1,050 planes. More than 1,000 are still in service. Depending on how the seats are configured, the 757-200 model could carry up to 228 passengers and the 757-300 could carry up to 289 passengers.

According to industry analysts, Boeing’s concept for a modified 737-8 MAX includes structural elements of the 737-9 MAX that give the 737-8ERX a maximum takeoff weight of about 88.5 metric tons.

Boeing stock opened Friday down 14 cents from Thursday's close, to $151.90 U.S. in a 52-week range of $116.32 U.S. to $158.83 U.S.