When you say strong, what exactly do you mean?
My brings 18hp twin runs good, and is strong, the tranny works, I’ve not yet pulled anything with it though because I plan on taking the motor off and putting it on that Craftsman….
I would think if everything remained stock it would last a while with proper maintenance.
If you constantly exceed the mowers stock limits (pulling big loads, improper maintenance ect..) it’s performance will decrease fast and not be as strong.
-CreechFan