I'm trying to find out what this old piece of equipment is that's located in the woods behind our house ever since we moved here almost 12 years ago, and was probably there for decades before that.  The wheel says National Drill Mfg. Co. and other pieces have designations like G2, G4 and G10.  I tried to Google the name, but couldn’t find anything.  I contacted someone knowledgeable with antique farming equipment and he thought it is a trencher used to dig trenches for laying drainage tile.  Any thoughts?