They were only used in 1978 to 1980 A-bodies. In everything BUT Chevrolet so dont waste your time looking at ElCaminos and Montes. Your best luck is with the Buick Century/Regal and the Olds Cutlass models.
I never saw any in four doors except wagons. I found most in Grand Prix's. Never seems to be any on cutlasses. LeMans is also a possibility. Pretty hard to find these days.