Jason, the small Briggs and Stratton, Lauson/Tecumseh and Honda engines all have the same mounting bolt positions and output shaft positions. That makes them physically interchangeable except for output shaft length and diameter. Some older engine designs do not conform to these standards, and substituting modern engines for them may require new mounting holes in the mounting deck, or a spacer plate with non-aligned upper and lower holes, or something more complicated if the old engine's crankshaft is too low rather than too high.
