COLORADO 5- or TU = Truck 6- or TA,TB = Tractor 7- or TR,TS = Trailer   1975 1976 1977 NORTH DAKOTA 1977 TRAILER STICKER   1978 1980 1981   c.1983 TRUCK SAMPLE c.1983 PAINT TEST 1983   1984 1985 1986   1987 1988 1988   1989 1989 Base TRACTOR SAMPLE 1991   1992 1997 c.1999   2000 2002 2005   PROTOTYPE