Does your sister have more information? Does she have her original birth certificate? My mother was forced to give up a daughter for adoption around that time. She has blocked out much of the details from her memory. She used a false name and the birth certificate listed the father having died in Vietnam and mother died at birth. Neither of which were true. She thought it was around June 25th 1966, but is uncertain of the actual date. She was not born in Missoula however as her adoption was black market.. she could have been adopted there.