We have an '05 and from what I have read, the '05 dif is the weak point but when it breaks, it can take out the back of the transmission in the process. When you think about it, an '05 is probably putting to the ground as much or more horsepower than my old COPO 427 Chevelle with headers and tuned and certainly more than the 427 had from the factory with its leaned out carb and retarded, slow advance curve. The stock setup is probably as strong as the old Muncies and 12 bolt rearends. Now, you add slicks, headers and the horsepower goes considerably higher. You can now expect things to break on the drag strip. With street tires, I am certainly not sweating. My tires don't hook hard enough to break anything. 2006 saw the weak parts beefed up.