SOUTH DAKOTA   1976 1977 TRAILER 1978   1979 1981 1982   1983 1985 1986   1987 1988 1989   1989 SUPPLEMENTAL BACK PLATE I've seen these on the backs of buses. There is a regular APPORTIONED plate on the front. 1990's TRAILER 1991   1992 1995 1996   1997 2001