 In 1973, the Kingston Rd route was renamed to "Downtowner" (today's 502 Downtowner) with a route extension to Bathurst station that was revoked in 1984.Also in 1973, with the renaming of "Kingston Rd" to "Downtowner", the Kingston Rd Tripper became simply "Kingston Rd" and ultimately the 503 Kingston Rd.From July 31, 2017, until February 16, 2018, the 503 Kingston Rd route was temporarily operated using buses due to a shortage of streetcars resulting from the late delivery of the new Bombardier Flexity Outlook streetcars.