[jeffschevelle]

My knowledge is limited to the 67 and earlier vertical flow radiators, but maybe how the tags were handled on those can lend a clue.

All 65-67 Harrison radiators (and probably earlier ones) have a small clip/tag with a 2-letter code attached to the upper lip of the core, which was the internal Harrison ID code for the core itself. So if the same core was used in 2 different radiators (such as a base 66 396/325 manual radiator and a base 66 396/325 automatic radiator), then the core ID tags on both radiators would have the same code even though the larger radiator ID tags would have two different codes (VX for the manual, or VY for the automatic).

The side straps on 66-67's (and perhaps earlier) also had a small clip-on tag with a 2-letter code which was the internal Harrison ID code for the complete strap assembly (the assembly of both sides and the bottom channel/tray). But you almost never see those tags because they were put on the very upper corner of the strap where it rolls over toward the top tank, so the first rag or sleeve or anything else that passes by it will snag it and pull it right off.

So, by analogy, is it possible that the codes on these hose clips have nothing to do with the clips themselves, but instead identify the part of the radiator to which those clips were attached? For example, if that clip is attached to a side mounting bracket then maybe the code identifies that particular side mounting bracket assembly (with the clips). If so, that would be killing two birds with one stone by putting the codes on the hose clips, which would eliminate the need to install a second clip-on tag to identify the part to which the hose clip was attached.

I'm guessing here, but since the two clips do look identical other than the codes, that seems like a reasonable guess.