According to the Standard Catalog of S&W, nearly all Model 586s were shipped with checkered Goncalo Alves target grips. The listing of product codes for the 586 does show one code, 103545, that specified 6" RR WO Pach Grip. The first part of that translates to 6" barrel, red insert ramp front sight, white outline rear sight, and (presumably, because the list of code abbreviations doesn't include "Pach Grip") Pachmayr Grips.
