Does anyone know the actual differences between the different vintages of the same Speedotron Powerpack? For instance, I had a 2403B pack that had the same measured light output as my 2403CX LV pack which was much newer. I could see differences in the switches and the connectors. Were there also internal design differences, or were they largely cosmetic? Similar question between the 102 and the 102A heads. Is there a difference? Your thoughts?