What aspects of the narrative voice in "The Name Means Thunder" clarify for the reader the time period in which David is telling these stories?

For the first time, in "The Name Means Thunder," David tells the reader something about what is happening in his present life as he narrates these stories--he is now an older man, in his early sixties at the very least, and he is soon going to see a doctor about his cataracts. He mentions that it has been more than fifty years since Pluto was "demoted" from planet status, which means that the year is now sometime after 2056. The reader understands from this that the narrator of these stories is an older person, many years in the future, looking back on his life as a child and young adult, around the time of the turn of the century.