Stan, I wrote you the note about the 70IND/Airport 25 Saturday evening but have a bit more info. In the Oliver book by C.H. Wendell there is a picture of an Ind tractor next to a picture of an Airport 25. The Ind has the mounting pads on the side of the front tub frame under the engine. (All industrial tractors had the pads) The 25 does NOT! If you check the pictures you posted, your tractor does not have the pads. I think this would reenforce the thought that it is an Airport 25. 
                                                    Good luck
                                                    Jim Thurnau
                                                     Galesburg, IL