If OP paid to upfare after purchase, presumably OP would have original receipts with original coach fares listed. Not exactly clear why OP seems to think these are coach fares (is it because of the fare basis codes?). If the Fare Details section is coming from the Delta email receipt, the main itin section of the receipt should list class of service booked along with booking class for each flight -- First Class (I), First Class (Z), and First Class (C).