Suction carb T (1930-1933) U (1940-1945) Suction carb WA (1930-1932) WI (cast iron; suction carb) (1938–1957) (industrial version of WMB) WM (cast iron; suction carb) (1936–1941) (WM, standing for Washing Machine) WMB (cast iron; suction carb) (1938-1957) (improved WM) WMG (cast iron; suction carb) (1937-1942) (WM with a generator) WMI (cast iron; suction carb) (1936-1941) (industrial version of WM) Y (cast iron; suction carb) (1931–1940) Z and ZZ (1931-1948) Many variations and submodels were available on the basic series mentioned above. Some variations include: gear reduction (gears bolted to the back of the engine to slow the speed of the PTO shaft) first offered in 1934, on models A B K and Z later on I U N and WI. Designated by an "R" after the basic model, then a 2, 4, or 6 to designate the reduction ratio. high speed models (higher intake capacity to run higher rpm) available on the A B K M R and Z series. designated with an "H" after the basic model. lightweight models (some aluminum parts to save weight) available on the A B I K R and Z series. Designated with an "L" after the basic model inboard marine engines (special base, no governor, thrust bearing on PTO side) available on models A B H I K N and Z. Designated with an "M" after the basic model. Some models also had forward neutral and reverse transmissions. These engines have an "T" or "G" after the "M" Aluminum models 6B (horizontal shaft) (1955–1959) 6BH (vertical shaft) (1953–1958) 6BHS (vertical shaft; suction carburetor) (1953–1958) 6BS (horizontal shaft; suction carburetor) (1955–1958) 8B (horizontal shaft) (1955–1958) 8BH (vertical shaft) (1953–1958) 60100 (horizontal shaft) (1958–1991) 80100 (horizontal shaft) (1958–1977) 80200 (horizontal shaft) (1960–1991) (horizontal shaft) and 190700 (vertical shaft) (1969–1997) 90000 97000 Europa OHV (vertical shaft) 100000 110000 120000 130000 140000 (horizontal shaft) (1958–1966) 170000 252410 (horizontal shaft) and 252700 (vertical shaft) (1977–1991) 280000 310000 OHV 400000 Twin Cylinder 420000 Twin Cylinder 460000 Twin Cylinder Industrial and commercial models 81300 and 81400 (horizontal shaft) (1979–1985) 82200 (horizontal shaft; Quiet Power) (1982–1994) 82300 and 82400 (horizontal shaft; Quiet Power) (1982–1994) 114900 (vertical shaft; Quiet Power) (1982–1991) 131200 (horizontal shaft) (1979–1985) 132200 (horizontal shaft; Quiet Power) (1982–1994) 131900 (vertical shaft) (1979–1989) 132900 (vertical shaft; Quiet Power) (1982–1995) 192700 and 193700 (vertical shaft) (1983–1994) 195400 (horizontal shaft) (1979–1994) 221400 (horizontal shaft) (1979–1985) 255400 (vertical shaft) (1984–1994) 281000 (vertical shaft)