Originally Posted by T-Mar

The presence of 531C indicates it's no older than 1983. Falcon totally revamped their lineup for 1988 with the Triathlon series being discontinued, so it should be 1983-1987, in which case it should be easier to narrow down from the components. Shimano 600EX (Arabesque) would be 1983. Fricition shifting New 600EX should be 1984-1985, while indexed shifting New 600EX would be 1986-1987.