poprad, A very nice find, congrats! '99 was a good year for Cannondale road bikes, IMHO. The CAAD3 and CAAD4 frames were the last of the high end models to have threaded steerers and, IIRC, the CAAD4 evolved into a threadless head set towards the end of the model year as there were actually few around here with the threaded head set.
Brad
PS FWIW my '99 R1000T was rebuilt as a hybrid when I found it, pretty sad.