In cab gas tank question

[CG]

I don't know jack about the tanks in our trucks. I do see threads where folks are talking about vented cap or no vented cap. My guess is there must be some difference in the tanks themselves.

Are the tanks all the same but the piece where the sending unit goes in different? Or is the vent a part of the fill tube?

Anyway Im just curious about stock tanks and how you tell the differences in years, and what years have a vented cap vs. pressurized (right terminology?)