A modular cutterbar assembly (200) and a work machine (100) with such is disclosed. The cutterbar assembly (200), comprising: at least one module (1002, 1104, 1108); a first end cap (1008) coupled to the at least one module (1002, 1104, 1108), the first end cap (1008) having an upper surface (208) defined between a first end and a second end; an inner cavity defined in the first end (1144) of the first end cap (1008), the inner cavity (1144) configured to substantially enclose a drive transfer mechanism; an aperture (1020) defined in the upper surface (208); and a coupler arm (1022) integrally formed with the second end of the first end cap (1008), the coupler arm (1022) configured to be coupled to the work machine (100).