Norm,
in looking at replacement motors, I noticed that the Jono and Johno replacement motors (Chondas or similar) show the mounting bolt measurements. Their 17.5 single has the same pattern as my motor, but their 20hp twin is different. They claim both of these motors have the Briggs and Stratton pattern. From your comment it seems that there are at least 2 Briggs patterns, for different sized motors?
