Looking at photos of when Big Boy #4014 was moved out of the museum onto the main line, I saw the last Metrolink train to pass on the line was pulled by an ex GO Transit F59PH. How many F59PHs did Metrolink lease/buy that are in the GO Transit livery?
Per this wiki link, Metrolink has leased 3 ex-GO logos.
http://en.m.wikipedia.org/wiki/EMD_F59PH
I'll admit I don't know how accurate that link is.