Replacement Engine needed

[Dmitchell]

I have a Koehler courage 21 Hp on a Husqvarna mower the engine slug a rod with 41 Hours on it. Warranty is out and Lowes is being horrible.
I know these engines are Bad now. What motor can I replace this with that will fit in the same area very tight layout on this yard tractor. Want at least a 21 to go back on the unit. Has anyone done this replacement?

 

[Rivets]

Please tell me how the unit can be out of warranty will only 42 hours on it. When did you purchase it. Who set it up. Kohler engines have a two year warranty. From what you posted two and two don't add up to four.