By Marina Malenic

Details of the Pentagon’s request for proposals to build a new fleet of aerial refueling tankers will determine the details of Boeing‘s [BA] KC-X bid, but one thing is certain about the company’s offering, according to officials: there will be no major modifications to the airplane it submits for the competition.

Boeing will offer either its 767 or 777 aircraft, depending on the specific requirements in a new draft RFP expected sometime later this month. In a previous competition with Northrop Grumman [NOC] and EADS–canceled last year after a political firestorm–Boeing’s critics referred to its 767-based offering as a “Frankentanker” because of its piecemeal construction from multiple airframes.

“We’re not doing the Frankentanker,” Rick Lemaster, Boeing’s KC-X program manager, told reporters during a briefing at the annual Air Force Association conference at National Harbor.

For instance, Lemaster said, Boeing would not alter either aircraft with a different wing or other major structural component.

He also said said the company had not chosen an engine manufacturer for the potential 777 offering. He said General Electric [GE], Pratt & Whitney [UTX] and Rolls-Royce were all candidates for the work.

Lemaster added that Boeing is incorporating lessons from its efforts on Italy’s and Japan’s tanker programs, as well as from its previous failed bid for the U.S. Air Force tanker work. Northrop Grumman and EADS won the U.S. contract, valued at approximately $35 billion, before Boeing’s challenge of the award was upheld by the Government Accountability Office. A fresh contest was considered last summer before finally being canceled by Defense Secretary Gates, who said a “cooling off period” in the contentious battle was warranted.

A primary lesson will be a renewed emphasis on cost, according to Lemaster. In the previous competition, Northrop Grumman’s aircraft scored points for its lower life-cycle and maintenance costs.

“We’re determined not to let that be a lesson that we didn’t learn,” Lemaster said.

Boeing had offered its smaller 767, but company officials announced at the Paris Air Show in July that they would offer the larger 777 if the new Air Force requirements call for more refueling capacity.

Regardless, minimal modifications will be made to either commercial jetliner.

“What we propose to the Air Force will be a low-risk solution,” Lemaster said.

Speaking at the same conference, Air Force Secretary Michael Donley said a preliminary World Trade Organization ruling earlier this month on a U.S. challenge to subsidies received by EADS parent company Airbus will not alter the Pentagon’s acquisition strategy for the aircraft.

“We see no need to make immediate adjustments in the RFP,” Donley said.