By TOM KRISHER General Motors Co. is poised to sign a deal to sell its Hummer brand to a Chinese heavy equipment manufacturer as early as Thursday afternoon, a person briefed on the deal said.Representatives of Sichuan Tengzhong Heavy Industrial Machinery Corp. have been in the U.S. for the past nine days working on final details with GM, and both sides hope to sign a definitive sales agreement on Thursday or Friday, said the person, who asked not to be identified because the deal is not final.The purchase price was not known, but GM said in its bankruptcy filing that Hummer might bring $500 million or more.GM spent 40 days in bankruptcy protection during the summer and has received about $50 billion in U.S.