No way to find the exact fare rules you purchased on Delta.com, but you can usually replicate them by searching for the same itinerary and fare classes using ITA matrix. Use this advanced routing code:
C: DL /f bc=s

(Remove the space between C: and DL – FT turns it into an emoticon if I don't include it)

Where the s in bc=s would be the "S" fare class for that segment. Use C: DL+ (adding the + after DL) if your flight is not direct. Then select your exact same routing (preferably the same dates) and click "fare rules" on the fare summary page to view the rules.

Note: you can uncheck "show only flights with available fares/prices" (forget the exact wording) to view the fare even if it's not available.