Best I recall it is 3/8 square x 3 1/2 to 4 inches long. End of the shaft is hidden up above the blade with a cup above and a small hole through the blade with a bolt into the end of the shaft. Seems like the shaft is broken up in there somewhere. Blade has to come off to remove from the top. Blocking the input shaft above, gears do not turn in gear box, but blade a lower end of shaft does. I repeat, blade has to come off to remove the rest from the top. A couple of years ago, the key sheared on the other side, and the whole thing fell off in the field. Bolt came unscrewed when the key sheared, and bolt, washer and blade were laying in one spot. miles
