Originally Posted by
javabytes
It used to be the case that any Classic inventory on AF/KL was bookable on DL. Not anymore. AF/KL seem to have split Classic into several buckets, all still named "Classic", and the flights you can get with SkyMiles are much more limited now. If you don't have an ExpertFlyer subscription, I'd suggest trying it out as you can search for award inventory, and if it shows on EF, you should be able to book it using DL miles. They've got a 5 day free trial.
There have been reports of even the KLM inventory showing on EF not being bookable with DL miles, although this can be the result of DL agents not knowing how to do it. Personally, at the end of last summer, I saw KLM award flights on delta.dumb, but was unable to ticket them online and the DM line couldn't get me these award flights either. It looked consistent enough not to be a problem with dynamic inventory availability.