I thought this was the S1 red shirt, until I noticed in No Exit (2x06), that it had TWO pockets (not just one), and that the pockets did up with a little button. I assumed, retroactively, that Dean acquired this different red shirt for S2, so I’m claiming it’s the version he wore in Bloodlust (2x03).
Brand Information: Possibly WindRiver.
In Bloodlust (2x03), Dean wears it from the beginning of the episode (driving to Red Lodge). He takes it off when he has to change into a suit to interview the sheriff and go to the morgue, but puts it on again afterwards. After he kills the vampire with the saw though, he takes off the shirt and does not wear it again for the rest of the episode.
In No Exit (2x06), Dean wears it for the entire time he is in Philadelphia.
Suddenly, many years later, the shirt possibly makes a reappearance in It’s The Great Pumpkin, Sam Winchester (4x07), where Dean could possibly be wearing it while he talks to Castiel in the park at the end of the episode.