I think I might have figured it out. So research is saying the UQ tag radiator was suppose to have the IL OO Harrison tanks. That has let that the original IL and OO tanks was a 4 core 3 row radiator. Would that have been correct for our 400's or would it have been 4 core 4 row? Those tank code were OL IL tanks codes.
I don't understand references to multiple cores. A core is singular; it is the cooling part of the radiator. Radiators were sized by the number of rows, 2, 3, and 4.
Maybe when they say 4 core, 3 row they mean the radiator has tanks that could fit a 4-row core, but presently has a 3-row core.
I did not understand it either but if you look at how all the harrisonson were made that was how that are listed. Example. 3 core 2 row, 4 core 3 row, 4 core 4 row.
They are remaking most of the tanks now with the correct markings here in the us. Here is a link to all the ones.