here's an '83-84 for salehttp://www.velociao.com/2012/colnago-nu ... 57-silver/
and here's a quote from another nuovo mexico owner
,apparently, was produced '81-85, a precursor to the '86 launched Master
''What Is It?
This is a Colnago Nuovo Mexico, the “new” refers to the crimped Columbus SL tubes. In about 1981, Ernesto Colnago decided to crimp the top and down tubes; something that bike builders had been doing to chain stays for decades. Though it was reported that the Nuovo Mexico was stiffer, there were some complaints of instability at high speeds. Crimping the down tube twice, which conveniently mimics the company’s logo, seemed to solve the problem. And given Colnago an idea for the future.''http://pezcyclingnews.com/?pg=fullstory&id=9885
It just shows how tricky it is trying to date Colnago frames from this period. The page you have linked says exactly what I said about your frame,
"The one featured here is a mid 80’s Colnago Nuovo Mexico."
Unless you have the original receipt from the first owner, you will never know for sure exactly which year it was built. During this period, Colnago first started cranking out frames by the thousands. Still, lovely frames and highly prized by collectors. Personally, I prefer red and the older style sticker on the seat tube. Oh, and definitely Super Record on a Mexico if not 50th Anniversary.