In a message dated 5/12/2005 5:26:40 A.M. US Eastern Standard Time, at-request at lists.antique-tractor.com writes: [AT] More John Deere 4020 questions NO the combine engines are not the same.. . HOWEVER my cousin put one from a 7700 in our grampa's 4020--- but you can't use a turbo's combine engine.. it sticks up to much