If I remember correctly just unbolt the braces and wiggle/lift up till the splines on the auger clear. There might be a bolt at the bottom but its fairly simple.
TNLee has it mostly correct - there are also 4 bolts that you need to remove on the bottom flange of the auger tube where it meets up with the cast boot/gearcase. Then it should pull straight off the splined shaft on the gearcase. There is also a cleanout door on the boot that you can open and get a pry bar in there if you need to "encourage" the auger shaft to slide off the gearcase shaft (I would be really surprised if you can get the auger to come apart without doing this.) Then before you re-install the auger, clean up both ends of the splines and put a little Never-Seez on the shaft before you slide them back together.
You were fortunate to find a picker with a sheller attachment. They were quite plentiful 10-15 years ago - no one wanted them, just wanted the husking bed. Then when scrap prices got high, many of them got hauled away. Now when people are looking for them again, there's not that many decent ones around anymore...
Did you get a husking bed with it too?
-- Edited by jdtom on Friday 1st of January 2016 06:47:43 PM