I put an AFX in my 1680 1992 model last year, same dimensions as the specialty rotor, you will love the AFX rotor, no more rotor rumble and a lot quieter, works great in all crops, company said it should only go in a long sieve machine due to more capacity but only have to drive accordingly, it made the combine a pleasure to drive in heavy straw conditions. E-mail me if any more questions.