Probably comes apart by removing a retaing snap ring at the head. They can sometimes be a PITA to get the rod out. I used to run a small chain through the eyes and use a blow gun to extend unit the packing head popped out. If it hangs up, whack it with a hammer. The chain is to keep from shooting across the shop floor like a torpedo when it pops. Make a long extension and use a cylinder hone to clean up and cross-hatch the cylinder bore. When you get all the packing installed, use a piston ring compressor to slide them in the bore without rolling or cutting them. If you grease/oil the packing enough the ring compressor, you can pick the whole thing up and drop the barrel end on the concrete floor. The impact will slide the packing head/rod right into the barrel.