Do you know what year it was madeIJ I think if I remember right they made two sizes of combines. A 18' head would be the bigger one and it being diesel most likely a newer one, or the very last of them. Our Oliver was gas. Oliver had a 525,535,545 and 5555. I know MM had one the size of our 525. It was about 85 hp and 75 bu grain tank. Sorry it was a long time ago, I have some books someplace on some of these combines. Ilnh