My Indian parts manual for 1936-1942 all models shows a part # 93050 Cylinder Assembly-front-std 1938 to 1942-45SS, and part # 93052 Cylinder Assy-rear-std. 1938-1942-45SS. My next Indian parts book 1944-1953 only covers 74 and 80 inchers so no numbers near it. I'd say 1943 45 incher. I'm no Indian expert so I'm sure someone will get you closer in year, but sure looks like an Indian to me.