Thats a vintage IH boxblade . From what I remember the yellow ones but not as heavy duty as yours were labeled and called IH Cub CADET #40 , #50, 60 etc . The red ones were called IH FarmAll . The model number would have been under the very back of BB under International name . I never seen that heavy duty particular model . Looks in great shape quite a find IMO.
Another thing in your search of IH is not to be confused with the other International line up of implements which came later out of Ohio , also known as WAC (World Agritech Corp) . Thats about all I know about your BB . Like I said nice find . Hope some of this info helps you in your search .