Boeing and Saab will announce “in weeks rather than months” that they will team up to offer the JAS 39 Gripen for the U.S. Air Force’s T-X future trainer requirement, according to sources familiar with the deal. Saab is apparently confident that the two companies will be able to undercut the cost of the closest rival contender, the Lockheed Martin/Korea Aerospace Industries T-50.

Other details of the deal are being closely held. The T-X program, aimed at acquiring some 350 trainers to replace the Northrop Grumman T-38, has been on hold due to budget cuts but is expected to restart in the 2015 budget.

The move is a major change to the line-up for the competition, for which Northrop Grumman has teamed with BAE Systems, offering the Hawk, and Alenia has joined forces with General Dynamics to promote the M-346.

Until now, Boeing had stated its intention to offer an all-new aircraft. However, a link with Saab became a possibility when the Swedish government launched development of the new JAS 39E version at the beginning of this year. Although the Swedish plan is formally contingent on Switzerland confirming its order for the fighter (in a referendum that is expected early next year), the Swiss deal has continued to pass milestones on the way to that decision. The JAS 39E is due to enter service in 2018.

Sweden and Switzerland both plan to order only JAS 39E single-seaters, but the two-seat 39F is a straightforward development.

The JAS 39F is fractionally larger and more powerful than the T-50, but also is more modern, with a wide-screen cockpit like that of the F-35 and a fully integrated helmet-mounted display. It is expected to cost less to acquire than the previous C/D variant and has been designed for easy maintenance and low operating costs. Swiss air force leaders say that its cost per flight hour is expected to be half that of the Typhoon and Rafale, its competitor for the Swiss order.

While no formal T-X requirement has been issued, Saab and Boeing’s action indicates that they believe any requirement under which the T-50 qualifies also could be met by the Gripen.

One industry source notes that a T-X Gripen also would be suitable for aggressor training, or as a companion trainer for F-22s and F-35s — which, unlike earlier USAF fighters, are not being acquired in two-seat versions. (The USAF has added T-38s to F-22 units in that role.) Beyond that, a source close to USAF leadership notes that “it is not a long step to an affordable air defense fighter to replace (Air National) Guard F-15/F-16 units.”

Boeing issued a statement that neither confirmed nor denied the existence of the Saab deal.

Update: On Sept. 12, Lennart Sindahl, Saab´s execuctive vice president and head of Saab’s Business Area Aeronautics, sought to clarify the company’s position regarding a potential teaming arrangement with Boeing on the T-X program using a Gripen derivative.

“With the new development of the Gripen E version we expect it to remain in that position for many years to come. But a great fighter aircraft does not necessarily make a good trainer. We remain focused on the continued development of the Gripen E and the fighter will never be a trainer,” Sindahl says. “As we stated previously, Saab always keeps its doors open to new business opportunities and if any of those should be further realized, they would be announced at the appropriate time.”

Editor’s note: This story has been updated to add comment from Saab.