Here's my Colnago Master Piu (acquired recently...likely from a reader of this forum)...patiently waiting its turn in line to get built up. The rear deraileur side dropout is stamped "Colnago" and "1D041".

FWIW, weeks ago, I located a post on the net (not sure if it was this site or not...but I copied it to my computer files as reference material) showing a Colnago rear deraileur side dropout with serial number 8E791. A reader guessed it was a 1988 model, stating "That serial number format is fairly common in the bicycle industry. Typically the first number represents the year, the letter represents the month and the remaining numbers are the sequence. So, the 79th frame of May 1988 would be my educated guess."

So, is it possible that the oringinal poster's serial number starts with a zero, not the letter "Oh". In that case, it might be dated 1990. Compare the style to mine...could they be one year apart? Though I can provide additional close up photos to help a fellow aficionado of classic era Italian bicycles, I can let you know right now that my bottom bracket cut out is quite different from that on the original post...mine is a cut out shaped like the Colnago logo.

Then, to pose a question in exchange for my entertaining photo post, can anyone confirm that Colnago manufactured Master Piu frames in 1991? Also, I recall reading on the Internet that the Piu frames might have been a European model, not imported to the U.S. Can anyone confirm this point as well?