Sorry folks. Wasn't aware this thread had been revived.
Super.......for the #22, bolt holes are 5" on center. All sides.
For the #12, they are 4" and 3 3/4".
Not much new to add since the original post, except I no longer cube meat for the initial pass. I cut pieces into longer strips of 2" to 4". They feed into the screws better vs having to push the cubes in by hand or using a stomper. Also, for some reason, the local store that sells fresh pork butts will sell the whole pork butt sliced as pork steaks for the same price as a whole butt. This makes boning them out and cutting them up run a whole lot faster.
By coincidence, a few days ago I happened to run across this youtube video series on sharpening your grinder blades and plates. It is a three part series. It is how I sharpen my blades, and includes the very good advice of using a sharpie pen to help find the flaws. The paper is straight wet/dry sandpaper available at most hardware stores, or better, at an auto parts store that caters to body shops that paint. They have good quality 3M paper.