Apparatus of the type which includes a frame having a base portion with a support surface, a ram reciprocably mounted to said frame for movement toward and away from said support surface of the base portion, and a die unit removably positioned on said supporting surface. The die unit is comprised of an anvil arrangement and a blade element slidably and telescopically associated with said anvil arrangement to cooperate therewith for the processing of a workpiece. The die unit is constructed so that the blade element may be releasably connected to said ram whereby interchangeability thereof is attained. In addition, there are provided means to facilitate the proper positioning of said die unit with respect to said ram. Said alignment means include protruding means provided on the underside of said anvil arrangement adapted to cooperate with correspondingly shaped recess means formed in the support surface of said base portion. The recess means are designed to receive said protruding means and thereby properly to position said die unit with respect to said ram along a first axis of alignment. Said alignment means further include additional means to attain proper positioning along a second axis of alignment.