Here's the best guide I've seen: Velo-Retro: Colnago Super Timeline

"1970
- Fork crown semi-sloping, flat front and back with two holes in the points at each side or very rarely, fork crown semi-sloping, curved front and back with two holes in the points at each side and with clubs in top
- "Eddy Merckx" style fork crown used in very rare instances
- "Playing card" club decal graphics. The Colnago Ace of Clubs logo was inspired by 1970 Milano-Sanremo victory in March by Michele Dancelli. Sanremo is The City of Flowers and the Ace of Clubs is known as the Ace of Flowers in Italy. Note that before Milano-Sanremo the club-shaped lug cutout was not a Colnago logo but only a club-shaped lug cutout. Using one of the four card suits, Clubs, Diamonds, Hearts or Spades for the lug cutouts was common with Italian frame builders.1970 October
- Eddy Merckx' first Colnago (October 1970), no chrome, supplied with fork crown semi-sloping, curved front and back with "C" and club in top of crown and two small clubs in the points at each side and head lugs with four small clubs in the sides1971
- Fork crown semi-sloping, flat front and back with two holes in the points at each side and clubs in top
- Fork tangs narrow, no cutouts (rarely no tangs)
- Club cutouts in all three lugs but club in lower head lug is now larger
- Hole in lower point of seat lug (last year)
- Bottom bracket shell with club cutout"