I went to grade school between 1967-1973.  Believe it or not, the
Mt. Lebanon School District never had regular school buses while I
was there through high school. I do distinctly remember the roll sign
on the PAT bus as "Tripper". After grade school I began walking to
jr. high and then to high school before I saved my money for my first
automobile(a 1975 Chevy Malibu). 
   The fact that Mt. Lebanon had no school bus service was always
disappointing to the students when a decent snow came along. Alot
of the school closings on snow days was directly linked to school
bus service. Seemed like we rarely missed any days at Mt. Lebanon
schools. 
  I don't remember how long PAT operated the school trippers in
Mt. Lebanon, but don't remember seeing them anymore when I went to
jr. high. 
  Thanks for the links to the articles Bill!

                              Mark