The front miter box came out easier than expected. It appears to be the same casting as a standard MK1 housing. There is no serial number on it. The split pins are 1/4″ not 3/16″ like the MK1 split pins. I put magnetic plugs on both boxes on day one to get some idea of what condition they are in. After about a week no metal came out on the front plug and a very small amount came out on the rear plug. The original plugs are brass square heads. I will put the brass ones back in when the bike is closer to being finished.
It is etched 1.586 which is the pinion setting depth.