I've had almost 40 cars so far and I've had three with exhaust manifolds that cracked... none of which are on the list I posted. I also work in the Land Rover parts and service industry and we rarely see cracked manifolds and we have Rovers rolling in and out every day. Yes, it happens and it's not a surprise- but there's no epidemic by any stretch. None of my Rovers have that problem either- but my 95 was misdiagnosed with a cracked manifold by the dealer when they installed my new gas tank, but they were wrong as the downpipe had just loosened up enough to blow the gasket. $6.58 and 15 minutes to fix.
So something broke- just get it fixed and get on with life. Your truck is just a few months shy of TEN model years old. How long do you expect a manufacturer to warranty something?