Coastbuster, that packing box will come out with a good slam.....there's no other retainer inside
use a strong vise to hold cyl base, put a scrap piece of steel in the rod eye and give it a good SLAM.......or you might be able to use the hyd rod like a slide hammer
You need that out to replace the piston packings (make sure you remember which direction the v-packings are in)