Caad 8 and optimo had sq BB..
I think they produced the 9-13 at the same time which were lighter....
Well, an update... I sold it anyway, decided I didn't need any more projects just now. One thing that put me off was the fact that it had a BB30 shell, and I didn't fancy faffing about with that. So at least some CAAD8 came with a BB30 setup.
AFAIK, Cannondale continued making the CAAD8 frame even after the subsequent numbers 9-13 etc were introduced. One difference was the '8 retained a straight 1.1/8" steerer tube and a carbon fork with alloy steerer tube, whereas all the other variants later came with tapered head tube and fork steerers. Am sure there were other differences, although I think previously Cannondale were known to use the same aluminium frame for variants of a model, so if you bought a Tiagra equipped CAAD5 for example you got the exact same frame as one delivered with full Dura Ace / Hollowgram cranks.