I heard of the revelation on the priesthood I think on June 2, 1978. The revelation was announced the day before, and the church did not waste any time in letting the missionaries know of the revelation. We received a call from our district leader, who was following the chain I am sure, making sure all the missionaries knew of the change as soon as it happened. Of course this opened to possible of us actively proselyting to people of African descent. However there were not a great deal of people who fit this category in Argentina. There were a few, and it felt good to treat all people the same.
We attended a zone conference shortly after and during the testimony period another missionary shared an experience. Shortly after hearing of the revelation and investigator questioned them as he had heard the Church discriminated against people of African descent. The missionary boldly responded, the Church extends the priesthood to all worthy male members irregardless of race. It was a great day, a testimony affirming day as we know that the prophets still receive revelation for our behalf.