Boeing said it's prepared to enter the next Air Force tanker competition with one of two planes.

The St. Louis-based defense unit of Boeing Co. on Monday offered details of its tanker proposals that would be either a KC-767 or a larger, converted 777. The latter would be comparable in size to the modified A330 offered by competitor Northrop Grumman Corp. and European Aeronautic Defence & Space Co.

"Boeing is ready to deliver maximum capability at the lowest cost," Boeing program manager Rick Lemaster said in a prepared news release Monday.

The Pentagon is preparing draft guidelines spelling out the rules for a new refueling tanker competition. Boeing will review the request before it decides what it would offer, said Bill Barksdale, a spokesman for Boeing Global Mobility Systems.

In February 2008, the Pentagon chose the Northrop/EADS proposal to build aerial refueling tankers that were larger than Boeing's proposed KC-767 tanker. Boeing protested and was supported by the Government Accountability Office, which found problems with how the contract was awarded.

The Pentagon decided to start over and reopen the $35 billion tanker competition.

"All that matters is the Air Force and what they want," Barksdale said. "If they want a bigger tanker, we have one that is definitely superior" to the A330.

Part of Monday's message is that "the other guys don't have a permanent advantage" with respect to the size of its tanker proposal, said Richard Aboulafia, an analyst with the Teal Group in Fairfax, Va. But converting the 777 into a refueling tanker would likely take time and money, he said.

"This is supposed to be an off-the-shelf procurement," Aboulafia said.

Boeing has produced some of the KC-767s already, including three that are in operational squadrons for the Japanese air force, Barksdale said. If it wins the contract, Boeing projects 50,000 jobs will be dedicated to the tanker. The planes would be built in Washington state.

Boeing officials provided the details at the Air Force Association's 2009 Air and Space Conference and Technology Exposition near Washington, D.C. The company also has launched a website devoted to its refueling tanker options called UnitedStatesTanker.com