What does this mean? Radiator question

I've seen that 325 part number discussed here before but don't know what its applications/differences are. here's the thing.. If you had a larger wider radiator, like the 26 inch wide found in later models, and a 16 inch diameter fan, a shroud there would direct air to those quite large areas not covered by the fan. The shroud for a 22 inch radiator directs air to 4 very small corners and a 2 inch by 12 inch strip that isn't covered by the fan. Thus the benefit is marginal. Good luck