The problem in looking on the internet is that B3 paint was not always the same color. B3 for 1972 and 1973 isn't the same as color as B3 in 1970.
For example, 1970 B3 was actually a poly color, meaning it had metallic in it
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For '72 it was not
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And then even if you look at different paint chips for different paint manufacturers, you get a difference. Yeah, I understand that having a real paint chip in your hand and looking at an image on the internet are two different things. But Basin Street Blue (plymouth), Blue Streak (Dodge) and Super Blue (Chrysler) are all the same color code for '72. But if you look at this chip chart vs the one above, those aren't the same color.
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Perhaps the "Petty Blue" reference was a mistake on my part, but there is a ton of speculation around that and quite frankly a lot of people use "petty blue" interchangeably with B3 for 1972 and 1973. My '72 Challenger was originally B3, and it's original paint is much lighter than what appears in the OP's first picture. There are several discussions about it here, like this one
paint code for petty blue