I've been doing some research for a build and will contribute what I learned regarding the end of the monoplaner line. I have a '95 and '96 catalog and looked up '93 and '94 at retrobike.
Last year of the Chorus monoplaner looks to be '93, then Chorus went to dual pivot. Athena kept the single pivot monoplaner in '95 , with the Athena logo present under the Campy shield.
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N = '96 Colnago C40, '04 Wilier Alpe D'Huez, '10 Colnago EPS, '85 Merckx Pro, '89 Merckx Century, '86 Tommasini Professional, '04 Teschner Aero FX Pro, '05 Alan Carbon Cross, '86 De Rosa Professional, '82 Colnago Super, '95 Gios Compact Pro, '95 Carrera Zeus, '84 Basso Gap, ‘89 Cinelli Supercorsa, ‘83 Bianchi Specialissima, ‘VO Randonneur, Ritchey Breakaway Steel, '84 Paletti Super Prestige, Heron Randonneur