Certainly not a normal Colnago, and the real maker if it's not colnago may not be easy to find out.
I'd think maybe very early 80's to mid 80's depending on some other info. The pros had top mount shifters on time trial bikes as early as 79 or so, but those bikes mostly got aero tubing around 1983-4. Consumer market bikes got top mount shifters on some models around 1982 or so and they were common by 1985.
I'd almost wonder if this bike had some sort of team history story to go along with it, The fillet brazing seems like a load of work for a production bike, but seems right for a time trial bike from 1981-2.
Steve Birmingham Lowell, Ma USA
Date: Wed, 08 Aug 2007 13:15:36 +0200 From: "Martin Appel" <firstname.lastname@example.org> Message: 10
a friend recently bought a "Colnago"-labelled frame of french ebay. I assume its pretty sure it ain't a Colnago, but what is it then? the unique features include: A Cinelli BB case with a 4-digit Serial nr. picture: http://forum.tour-magazin.de/attachment.php?attachmentid=85628&d=1186433527
head tube area is fillet brazed picture: http://forum.tour-magazin.de/attachment.php?attachmentid=85756&d=1186533272
seat cluster is fillet brazed and seatpin is fixed with 2 bolts Pictures: http://forum.tour-magazin.de/attachment.php?attachmentid=85754&d=1186533272 http://forum.tour-magazin.de/attachment.php?attachmentid=85627&d=1186433527
rest of the frame is lugged
dropouts are nicely brazed in, with an "open end" to the tubing. http://forum.tour-magazin.de/attachment.php?attachmentid=85759&d=1186533272
i have not yet seen a frame with these features. KOF? Casati? Japanse?...
any hints? :)