A many-body Gupta-type potential, derived by fitting bulk experimental parameters for aluminum, has been used to study geometric shell clusters of aluminum with icosahedral, decahedral, fcc, and bcc packing. The stabilities of fcc-like octahedral clusters are compared with cuboctahedral and regularly truncated octahedral clusters. A stepwise pattern of truncation is observed and truncated octahedra are predicted to remain the preferred fcc-like structure until complete transition to the bulk fcc lattice. (C) 2000 American Institute of Physics. [S0021-9606(00)71110-X].