Transfer Case problems of the 2016 Kia Motor Sorento

While passing, sudden loss of all power. The check engine light came on. From that point on, very low power. When I got home, there was a fairly loud engine knock and oil coming from tail pipe. Took car to independent shop who diagnosed the issue as rod knock. Had the car towed to kia dealer who then said it needed a new engine. Only 82,000 miles on vehicle. Kia covered the parts and labor to replace. When the shop dropped the engine, they noticed the drive splines on both the awd transfer case and transmission were both rusted and all teeth sheared off on the fwd side of the spines. Rwd still intact. Kia would not cover neither would the extended warranty company because of the rust. That is a sealed unit with multiple rubber gaskets. How could it possibly have rusted? this is a major design flaw as there should been adequate heavy lubricant as well as sealing to prevent these parts from rusting. New transmission required $1800, and new transfer case would have been another $2500. Chose slightly used unit for $1000. It took almost 8 weeks to resolve. Now car is leaking oil on to exhaust. Back to dealer it goes. . .