Hi Barry, this is a curly one....presuming that the output shaft free end of the Briggs is the same diameter as the Tecumseh; that the mounting holes for the Tecumseh line up when the Briggs is placed in the same position, this would not be a difficult swap.
Before we get the tools out, can you please post some pics of both engines and particularly the cutter clutch attachment to the engine shaft of the 17" machine and how the Diplomat is connected .
We can then work out a plan for you to proceed.
