Nacional does not sell brisket.................Brisket is called Pecho de Res...If there's a Supermercado Nacional nearby, they seem to use decent butchers for their domestic beef. They also have pretty good imported beef, but I doubt they'd have brisket.
Guys, the OP isn't a jewish guy from NYC, he is from texas. He wants to dry rub a brisket and then smoke, probably for 12 - 24 hours. Whole different deal.Talk to the german butcher in Sosua, tell the wife you want it to cook with potatoes and cabbage.