You are not clear in your facts.
If your grandfather had purchased 13 acres and 8 acres of land in the year 1960 and 1971 and registered it in the name of his elder son, then how can he distribute the said land to all his three sons? If at all, the elder son in whose name the property stands registered has to gift it to his other two brothers through a Registered Deed. Therefore, your saying that the grandfather distributed the land equally among all his sons and pass books have been issued is not understood.
Without knowing the exact facts of the case and the documents in possession of your father, it will not be possible for any one to give any useful suggestion.