Boeing has sold two more C-17 transports to an undisclosed customer, but it will likely end the year with eight unsold white tails.

There are 10 Boeing C-17 airlifters in various stages of assembly at the company’s Long Beach, California, production facility.

Two of the aircraft are spoken for by an unnamed customer, Boeing says. Boeing is trying to sell off the other eight white tails, which will be the last produced before the factory is shuttered sometime in the summer of 2015.

The 279th – and final – C-17 fuselage will be mated to its wings in January or February, programme spokeswoman Tiffany Pitts tells Flightglobal. The operation is California’s last remaining aircraft production line and the lone widebody military aircraft production line in the USA, according to Boeing.

“When we do that major join of the airplane with the wings, it will be a big deal, because that is the last time you will see one of these aircraft come together as an airplane in this facility,” she says. The Long Beach, California site opened in 1941 as a Douglas factory.

At least two countries – Australia and Canada – have publicly announced an intention to purchase a C-17, though neither factor into Boeing’s future planning, Pitts says. Until contracts are finalised, the number available remains eight, she says. The Royal Canadian Air Force already has four C-17As, according to Flightglobal’s World Air Forces 2014 directory.

Canadian news outlets reported earlier in December that the air force would buy one C-17 with money left over at the end of 2015.

Australia is further along with its bid to purchase C-17s. The US Defense Security Cooperation Agency in November announced Australia was approved to buy up to four C-17s and support equipment for $1.6 billion.

The Royal Australian Air Force already operates six C-17As. The UK has eight of the type while both Qatar and the United Arab Emirates own four and six, respectively. Another three are owned by the NATO-led Strategic Airlift Capability consortium. Kuwait has at least one on order with the option to purchase another.

India has ordered 10 C-17As, which will eventually make it the largest fleet outside the USA.

“The proposed sale of additional C-17As will further improve Australia's capability to deploy rapidly in support of global coalition operations and will also greatly enhance its ability to lead regional humanitarian and peacekeeping operations,” DSCA says.

Boeing has plans to store any unsold C-17s following closure of its production line, Pitts says.

“I’m hoping they all will be sold before then, but we’ve had plans in place for a very long time to store and maintain the aircraft if that doesn’t happen,” she says.