I know this topic is ancient, but here's some additional info:
1952-1953 4-cyl & 161 flatheads took Harrison radiator, Willys part number 803268.
1952-1953 F-heads used Harrison radiator, Willys part number 803256.
1954-1955 226's used Willys part number 905846 (Harrison?).
I knew 226's used a different radiator, but had no idea that different radiators were used for the two different 161 engines.