L-25's police cruiser is a Mercury as opposed to a Plymouth which is the norm for Adam-12/LAPD. The only other brand of car used was an AMC Matador. The Mercury Montego was used by real life LAPD at that time.
Code 6 = away from vehicle and radio communication, investigating at location specified.
404.6 refers to the section in the California Penal Code. It deals with intent to incite a riot.
Code 2 = urgent, no lights or siren.