I just bought my first combine, JD9410, I need to buy a bean head and was looking at 920F, then a JD shop manager told me the 620F was so much better. My question is will the 620F head fit right on it, I don't have pto shafts on my feeder house, it's gears, and I plan this year to use an older 444 corn head with gear/chain drives, I have always hired my combining done, and am dumb at all of this stuff. Does the "F" stand for full fingered auger or not? and can I convert my feeder house to fit the 620F, but then have convert back to go to the old corn head, should I just try to find a late model 920F?? How much difference are there in the heads? thanks