If I remember correctly, 1970 -1978 cars, with the exception of SE's, all had chrome trim. The 1979 - 1981 T/As had blacked out trim, but only the Trans Ams. The other 1979 - 1981 Firebird models didn't have blacked out trim (Formulas may have, but it may have been an option). The blacked out trim in the later years was used to make the cars seem more aggressive. Also, I believe GM wanted to get away from the bright work, however, I may be wrong about that. Plus what Rick said (he got done typing before I did).