I was thinking like TaxGuyBill too about whether this is a partial disposition of assets in a GAA. You might want to review the list in Pub 946 to see if your scenario fits into one of the criteria for when a GAA can be terminated and when assets can be removed from a GAA.

If this is a partial disposition and the GAA isn't terminated, the way I understand it, the proceeds are reported with a zero adjusted basis against it and there is a component that is potentially taxed as ordinary income. Also, the GAA basis and reserve are kept intact and are unaffected with depreciation continuing to be calculated on the full amount of the GAA until the final disposition. Then in the final year, you will factor in the amount already recaptured. In other words, basis and reserve aren't allocated in the year(s) of partial disposition.