Ronster
In '89 I broke the front axle housing (casting) on my '58 2cyl Deere 420, and Deere had one in parts. In '95 the engine block and head were both replaced along with a complete engine overhaul, and all parts were available in Deere parts inventory.
In '91 I rebuilt a '59 Deere 420 crawler, having to do extensive part replacement to the clutch, brakes, and driving gears, as well as a couple gears in the transmission (a previous owner didn't believe in putting snap rings on to hold gears in place, and thought it cute to weld the gears onto the shafts /forums/images/graemlins/crazy.gif ), and all parts needed were available from Deere. Just my experience with Deere in the tractor arena.
In the lawn tractor arena, I replaced grill, hood, wheels, and transmission gears on a '69 110 lawn tractor with new parts from Deere in '2001. I'm pleased. Not like boat motor parts, that stick around for about 10 years in inventory.