I got this unit at an estate auction back in June in middle Tennessee where there was a decent collection of Allis Chalmers stuff. To me (from my Google Searches) it looks similar to a Fertilizer Side Dresser for an Allis Chalmers G tractor, but it doesn't look exactly like the ones I've seen in pictures. Please chime in with any information you may have.
I apologize for the bad quality pictures. It was getting dark outside.