So far, AFAIK DL doesn't have PE to South America. PE (which DL calls PS = Premium Select, not to be confused with C+ which are just seats in the front of coach with more legroom even though different fare/booking classes are used) is available on the A350 and 777 aircraft while, for instance, DL uses the A330 for the ATL-EZE route. This is likely to change as DL reconfigures some 767 aircraft to have suites and PS cabins, but AFIK DL doesn't currently use the 777 or A350 on its South American routes.

ADDED: To be clear, the dimensions given above for DL 101/110, the ATL-EZE and vv route, are for C+ (NOT PS) seats. PS seats are wider than coach, for example 8 across in the PS = PE cabin versus a generous 9 across in C+ and coach on the 777. Essentially DL C+ is just what UA calls Y+ And AA calls MCE. These are NOT premium economy products.