There is a lengthy thread that you may find helpful regarding DL elites receiving AS upgrades with a lot of nice information.
Consolidated: Upgrading on Alaska Airlines as a Delta elite
Originally Posted by
flyingfran
Do the same criteria apply. Would I receive an upgrade before an Alaskan FF if I had greater status or had made my reservation earlier?
The seating chart for the Alaska flight shows up on the Delta web site. Is it not correct? Do I have to do something with Alaska to select my own seat? I did not understand what I need to do regarding contacting Alaska for my Alaska confirm # or waiting for Alaska to confirm status with Delta.
I gather I am going to have to do something in addition to just selecting the purchase button and then selecting my seats?
FWIW, there have been flights that I have booked on DL and I was able to select a seat on an AS (actually, QX) operated flight right on delta.com. I always call and get the AS confirmation though just to be sure it went through. It seems as if AS and DL seatmaps are linked but do not quote me on that.