I guess it's self explanatory. But I have a flight from MSP to BOS, via ATL (yes, I did it for the miles) and the seats are K class. Will I be able to upgrade them at the airport?

I know the link to a "Delta Upgrades" page, http://www.dataton.net/DeltaFareClasses.html
but I've had it bookmarked for awhile, and I"m not sure how accurate it is.

Rita