Campagnolo production year for a crank

From 1958 - 1972 Record crank arms were not dated.
From 1973 - 1979 the year is the last digit in a diamond.
From 1980 - 1984 the year is the last digit in a circle.
An "11" in a rectangle means 1985, an "22" in a rectangle means 1986  and "33" means 1987.

More about BCD 144 and BCD 151

BCD explained.

Chainrings are most often measured in reference to their Bolt Circle Diameter (BCD).
BCD is literally the diameter of an imaginary circle that connects the centers of all the chainring bolts.