There are a few places where this information can be gotten. Original owners manuals contain some part number information, but no dates. The best bet is the Master Parts Catalog...there was a MPC for all of the corn shellers, a different one for the feed grinders, etc. The MPC contains all of the casting numbers and what years they were used. You can pick these things up on eBay fairly regularly. I think original manuals go for around $20 and MPC's for $30-40. I like looking through the MPC to see what sort of optional equipment was available, such as a special electric flywheel that had a V-belt groove machined in it to be powered by an electric motor, and the "popcorn special" picker wheel inside the machine...