OUTLINE: Radioimmunotherapy plus 2-Drug Cytoreductive Chemotherapy followed by Bone Marrow Transplantation with, as indicated, CNS Therapy. Iodine-131-labeled Monoclonal Antibody BC8 (anti-CD45), 131I-BC8; plus Busulfan, BU, NSC-750; Cyclophosphamide, CTX, NSC-26271; followed by Allogeneic Bone Marrow, ABM; with, as indicated, Intrathecal Methotrexate, IT MTX, NSC-740.