What Is the Cost Basis for a Revocable Grantor Trust?

[whenry5]

My Grandfather placed his farm in a revocable grantor trust shortly before his death in 1980. The trust was included in his estate. My Mother was designated as a beneficiary of the trust for her care and maintenance.  The trust specified that at her death the trustee was to divide and distribute the assets in the trust to my two sisters and myself free of any trust. My mother died 15 Dec 2011 and the assets were deeded to us in November 2012. What cost basis do we use for calculating capital gains when we sell assets from the trust?  Do we use the value when my grandfather acquired the property, the alternate value used for the estate tax, the appraised value of the property when my Grandfather died, or a stepped up Fair Market Value at the time of my Mother's death, 15 Dec 2011, or when the property was deed to us in November 2012?

[robtm]

I would think that the cost basis would be when you actually gained control of the property in November 2012.