General Motors Corp. will have a substantial say over the ability of Raytheon Co. to make major acquisitions and sell assets for two years after Raytheon buys GM's Hughes Electronics subsidiary, according to a Securities and Exchange Commission filing. Raytheon, a Lexington, Mass.-based defense company, is on the verge of acquiring Westchester-based Hughes' defense business in a $10.1-billion transaction. Raytheon would grant GM certain veto rights after the complex acquisition takes place, according to documents filed this week. GM negotiated the provisions to ensure that the Hughes transaction maintains its tax-free status under the Internal Revenue Service Code, the SEC filing said. By some estimates, GM and its shareholders would be liable for more than $1 billion in capital gains taxes if this status is lost.