Denny,
Thank you for your analysis/interpretation.
Grant,
Thank you for your autopsy report.
Now, what do you think the differences in the part numbers might relate to? My guess it that the differences are not due to the style of label (white label vs painted words). However, the differences may be due to name on the label (Radiator Overflow Condenser vs Radiator Overflow Return Tank) and due to change in pressure cap rating in 53/54?