My 93 R42 only came with the short-tooth standard chaffer and dealer said I didn't need anything else, but when I had F2, I always used long-tooth on corn so I had my doubts about not needing it for R42. Well I bought a long-tooth square end for R42 and did not like it. Seem to get a lot more pieces of cob in the hopper so went back to standard but I did do the chaffer mod to the front 6 rows of teeth. So far it seems to work quite well. Dealer said that long-tooth square end was good for high moisture corn. Remember, this is what works best for me. I'm sure there are other opinions. My friend Nick only uses the square-tooth for corn and beans on his 52. Our machines do not have the longer shoe. It all boils down to trial and error. Best of luck, Dan