To keep from filling house yards w/ cobs I raised the rear door on my 7010. The new xx20 bines only have the door if ordered as an option. As an attachment, there are 2 kits for the 20 series. The first one [I put this one on my 7120] is a couple hinges, a open latch and a closed latch. About $90.00.
The second one [called a windrow kit] includes the above stuff but adds tin work to the inside to funnel stuff better. About $800.
I put the cheap one on and it works great. Couple seconds to open or close. A lot faster and easier than lifting and lowering spreader.
For large acres of lets say wheat, u may want the expensive full windrow kit.