 A previous attempt to replace the W48 with the W74 munition was canceled due to cost.Originally envisioned as a dual-purpose weapon, with interchangeable components to allow the shell to function as either a "standard" fission explosive or an "enhanced radiation" device, the warhead was developed at Lawrence Livermore Laboratory starting in 1977.The eventual prototype round had a yield of two kilotons in a package long and weighing , which included the rocket-assisted portion of the shell.