WHICH will prevail: B-2 bomber or M-1 tank? "Star wars" or the F-14 fighter?Call it the battle of the new vs. the tried and true. As Congress considers the defense budget in the wake of the Gulf war, lawmakers are debating two very different visions for the Pentagon's future. One, pushed by the administration and a number of key senators, emphasizes pressing ahead with next-generation systems such as the B-2. Another, backed by the House, calls for holding off the rush to newer technology while continuing purchase of some major weapons the White House wants to stop buying. In recent weeks the rhetoric of this battle has escalated sharply. President Bush has charged that the House approach to the defense bill emphasizes pork-barrel politics, not defense of the American people. Rep. Les Aspin (D) of Wisconsin, chairman of the House Armed Services Committee, says the administration wants to put all its eggs in the basket of new systems "before it's prudent." But the argument isn't just Republican vs. Democrat. Sen. Sam Nunn (D) of Georgia, chairman of the Senate Armed Services Committee and perhaps the most influential defense voice on Capitol Hill, backs continued B-2 production. He wants to deploy a limited, phase-one Strategic Defense Initiative (SDI) - something that's anathema to most House Democrats. "The real debates are within the Democratic Party," says Greg Weaver, senior defense analyst at the SAIC Corporation Unlike the contentious budget years of the late 1980s, the total amount of money to be spent on defense isn't an issue this year. Last year's budget summit set a limit of some $213 billion for fiscal 1992 defense authorization funds. The debate, instead, is about priorities. And with the Gulf war having intervened since the White House submitted its original budget request in January, all sides are now scrambling to claim that the fighting validated their approach. The full House approved its version of the defense bill in late May. The largest cuts of the White House request were made in big strategic programs: All $3.2 billion proposed for B-2 production was denied. Some $1.7 billion was stripped from the SDI budget and work on space-based "Brilliant Pebbles" interceptors prohibited. With the total amount of defense spending already set, these cuts freed up big chunks of cash that had to go somewhere. The House put them largely into continued production of conventional weapons. Among other things, money was added for continued upgrading of F-14 fighters and production of M-1 tanks and OH-58 helicopters. The White House wanted to end all these programs. Mr. Aspin defends keeping these production lines open, against Pentagon wishes on the grounds that it keeps the US defense industrial base healthy, insures against unforeseen problems in systems now under development, and provides price competition for next-generation systems. But Mr. Bush and others have cried "pork," pointing out the large number of jobs at stake. The New York congressional delegation, for example, has fought fiercely for years to keep the Long Island-built Grumman F-14 in the budget. Even those who believe there's no reason to rush next-generation weapons such as the F-22 fighter and the B-2 bomber into production admit the House approach makes sense from the point of view of votes. "It's good budgetary policy, and good politics," says John Isaacs, a defense analyst at the Council for a Livable World. Bush has threatened to veto a defense bill that doesn't contain the money he wants for B-2 and SDI. And the Senate Armed Services panel, under Senator Nunn, has produced a version of th e legislation that is much more to the White House's liking. Along with $3.2 billion for B-2 production, it would spend some $4.5 billion for SDI - and mandate deployment of SDI-developed interceptor rockets at a single anti-ballistic missile site, keeping within the bounds of the 1972 Anti-ballistic Missile Treaty. Nunn seems convinced the US needs some sort of protection against a limited nuclear threat, such as from an accidental Soviet launch or a third world power. If his deployment compromise is approved by the full Senate and survives conference with the House, it would mark the biggest event in SDI's life since it was initiated by President Reagan. The Senate and House will likely sit down to hammer out differences between their two bills in September; the inevitable compromises on B-2 and SDI funding must then pass presidential muster if the bill is to avoid a veto.