The seatmap shows the config for the ex-GF/OZ 763ERs (ships 1501-1506 and ship 1521) which only have one overwing exit. All the other DL
763ERs still have two exit rows (rows 20 and 21) in Y. They're being 'safe' right now in only displaying the GF
/OZ 763ERs because these only have 30 BizElite seats as opposed to the 36 on the regular/majority 763ERs (and they don't want to mislead BizElite passengers that row 6 may be there when in fact it won't be should the GF
/OZ a/c be used). They usually can't definitely confirm which type of 763ER would be used until the day before or the day of departure. Hope this helps.