You need to refer to all of the IRS information for the specifics of how to defer. I believe you should just input the date of sale, but no sales price. That stops depreciation and removes the assets from the depreciation in the future. You will be able to see the accumulated depreciation on the depreciation schedule and use that to compute the deferral. 

You can then do whatever attachment is necessary to show the deferral. I have no expertise there and have not read beyond this page https://www.irs.gov/newsroom/irs-drought-stricken-farmers-and-ranchers-have-more-time-to-replace-liv...