De Gribaldy decals would indicate the frame as 1984 or 1985. Value will depend on whether it is a team replica, an actual team bicycle or a genuine bicycle ridden by Sean Kelly. If it's one of the latter two, you'll need some documentation to prove it and realize it's true value. If it's a bicycle ridden by Sean in one of his numerous Classics wins, if it hasn't been restored, and if you have the documentation to support ithe history, then it will attract a lot of buyers. However, I would not want to guess how high this could go for at auction!