Calculation of long term capital gain

Hi Friends,

Mr.X has a land of 120 Sq.Yads purchased in 1967. He transferred to Mrs.X by way of gift in 2002. Later, Mrs. X sold Mr.Y.    

What is cost of acqusation of land to be taken for calculation of Indexation?

Whether the we have to take Value as on 01-04-1981 or Cost of previous Owner( Because it transferred by way of gift).

Thanks in Advance.