I know for a fact that no 2820 boats have been made in anything other than deep v. They didn't add the D for a while because there was no reason to designate the deep v, since they all were made with the DV. First hand from Parker. Also, count the strakes. There will be two, not one.
FYI, I have a 2007 2820XL and did significant research prior to buying it. I have some documents from Parker if you PM me your email.