I know this has been disscussed here before and I did do a search and read some threads on the subject but I am thinking about puting a 7.5 Fisher on my `05 Sierra Denali that just turned 100K miles.I know the truck will handle the weight and I have towed heavy trailers with it with no problem.My concern is the awd t-case,I know a member here named Lodogg had one and ran it with great success, my question is has anyone here seen a t-case in a Denali fail from plowing?