# is the horsepower of engine
K is Kohler
On is Onan
Y is Yanmar (diesel)
Year Engine Serial Number
1983 20 On 220,001-285,000
1984 20 On 285,001-315,000
1985 20 On 315,001-360,000
1986 20 On 360,001-420,000
1987 20 On 420,001-475,000
1988 20 On 475,001-595,000
1989 20 On 595,001-999,999
1990 20 On 010,001-100,000
1991 20 On 100,001-110,000
1992 20 On 110,001-120,000
Year Engine Serial Number
1975 19.9K 30,001-55,000
1976 19.9K 55,001-70,000
1977 19.9K 70,001-80,000
1978 19.9K 80,001-95,000
1979 19.9K 95,001-120,000
1980 19.9K 120,001-155,000
1981 19.9K 155,001-190,000
1982 19.9K 190,001-222,000
Year Engine Serial Number
1984 20Y 285,001-315,000
1985 20Y 315,001-360,000
1986 20Y 360,001-420,000
1987 20Y 420,001-475,000
1988 20Y 475,001-595,000
1989 20Y 595,001-999,999
1990 20Y 010,001-100,000
1991 20Y 100,001-110,000
1992 20Y 110,001-120,000