Originally Posted by
bike recyclery
Couldn't quite tell, but that makes sense! In that case, does anyone know what the 21 stands for?
21 is a date code, or probably better stated a "batch" code. This was during the dark days where demand for Campagnolo fell off a cliff. Shimano 7400 was pushing Campagnolo to the side.
'86-'88 is a good period for these. Distributors had much on hand and unlike bread, did not have to rotate stock so vigorously.
You will also find 31 in a square, and 11 in a square.