Try the San Telmo market. One of the stalls inside is a pork and beef place, and they have what looks like ham hocks and such hanging from hooks. There may be shanks, too.If you haven't been there, the market is in the interior of the block bounded by Defensa, Estados Unidos, Bolivar, and Carlos Calvo. There are entrances on each street. Depending on which one you use, you may have to wind your way through antique stalls and other non-food passageways to reach the food market.