which means the decals I ordered are wrong, still for a cheap rebuild and DIY spray job with £10 on decals i don't think its a deal breaker, i think i prefer the 2.8 decals anyway, always assumed this frame was around 93-4 but i guess 1990 is a nice round number!
I think you're right! serial is:
66311901649 which according to vintage cannondale and correlating with frame size etc
6 - drop out spacing 126
63 frame size
1190 - november 1990
1649 frame number
which certainly looks like the frames here with the integrated seatpost bold and cable guides on top like you mention
http://www.vintagecannondale.com/year/1990/1990.pdf
which means the decals I ordered are wrong, still for a cheap rebuild and DIY spray job with £10 on decals i don't think its a deal breaker, i think i prefer the 2.8 decals anyway, always assumed this frame was around 93-4 but i guess 1990 is a nice round number!