Wikipedia, if you can believe everything they print, says,
The PA-24-400 Comanche 400,while identical in plan form to other single-engined Comanches, is structurally strengthened, primarily in the tail. The aircraft has an extra nose rib in the stabilator and in the vertical fin. The stabilator, vertical fin, and rudder of the 400 share virtually no common parts with the 180, 250, and 260hp (190 kW) Comanches. In addition, the 400's rudder is aerodynamically balanced in a manner similar to that of the Piper PA30 Twin Comanche and does not have the lead external balance weights of the lower-powered single-engine Comanches.
No mention of a PA24-400 structural failure in Australia in the ATSB accident report database that I can see.