on the 16 h.p. briggs vanguard in my max 2, the motor shaft i assume is a 1'' x3'' keyed and tapped for a 3/8'' bolt to hold on the clutch. engines for replacement in the 20 hp. range are hard to find with the tapped shaft. you need that bolt to hold on the clutch right ? any ideas on model # s etc. thanks , and have a super new year !! johnboy va.