Variable cross-section combine feeder slat

A combine feeder slat having a first base, a second base, and a slat body. The bases are located at respective ends of the slat, and have respective upper and lower surfaces. The slat body extends longitudinally and connects the bases. The slat body has a variable profile as viewed along the longitudinal direction, that transitions from a first profile shape at the first base, to an intermediate profile shape between the first base and the second base, to a second profile shape at the second base. The intermediate profile shape includes a front lip, a rear lip, and an upward-facing concave projection that connects the front lip to the rear lip and extends below an attachment plane defined between the first lower surface and the second lower surface. The first base, second base, and slat body are made from a unitary metal part.