The Parker 4000 gravity wagon was manufactured in the 70s and 80s, and featured a double door construction for additional capacity and unloading flexibility. You may unload from either door, or both, by selecting a tipping side. Price start: $10800 Extension Price: $1200 Capacity: 375 bushels/13215 liters without extensions, 440 bushels/15505 liters with extensions Features: Rear hitch, two unloading doors.