Vintage 1981-1983 Rare Bianchi Campione Del Mondo

Description

81 Bianchi
. Apparently it is using a serial number system most often
seen on 82 models, and the large production number of 9960 suggests that it was made very late in the year, plus the letter of "M"
Plus all 1981 models that came into the US had a "gold" ID label on the seat-tube located just above the bottom bracket. Yours does not.
Bianchi never offered a CDM model like yours to the US in 1981. Granted several of the components on your bike were switched out from the stock originals, but all of them appear to be post-81.
So it is a wildly different type of bike
The tires are flat and need replaced
Overall good shape and would be good now or restored
Approximately 21 inch frame or 53 cm