The Adam-12 uniforms changed because the real LAPD uniforms did
The show wanted accuracy down to the tiniest detail!
When the classic police drama Adam-12 returned for a second season in the fall of 1969, it premiered slightly altered from its original form. There were a few minor changes only eagle-eyed fans would notice.
For one thing, the two-man patrol car referenced by the code word "Adam" changed from a 1968 Plymouth Belvedere in season one to a 1969 model in season two. As the cars are virtually identical, it went mostly undetected.
Something a little more noticeable, but still tiny, happens in the opening credits. The dispatches heard in voiceover at the very beginning of the sequence (recorded by real-life police dispatcher Shaaron Claridge) were cut from four in the first season to only two dispatches in the second season.
Perhaps the clearest change, even if it's also subtle, was to the uniforms worn by officers Pete Malloy and Jim Reed. The hats were much more rounded and each officer wore a name tag from season two onward.
Adam-12 changed the costumes to better reflect the real Los Angeles Police Department, who were also updating their uniforms at the time.
One purely functional change was the metal used in the buttons. In season one, they used shiny brass. They were switched to nickel for season two, which cut down on reflections, especially from streetlights at night. The buttons were so accurate that they even had "Los Angeles Police' written on them!
Did you ever pick up on these changes?