Ed: The 500 is better than the series 3 and the 800 is better than the 500. Your 318 can be converted to fit the l's and M's and right now they are in demand for that conversion. If you install a Tiger Jaw 2000 knife to your series 3 head you will gain quite a bit in performance and I would include along with that a 2 1_2 inch or 2 3_4 inch plastic hose to act as a rock guard_grain saver.