Problems I've noticed at work with those Cadillacs are the AWD trans mission and transfer case is too weak for the torque of the 6.0 liter engine.
The rear exhaust manifold bolt (nearest the firewall) on each cylinder head has a tendency to snap off at any given time and is $$$ to repair. Not removing and replacing the broken bolt could lead to OBD codes related to catalytic converter threshold efficiency or OBD codes for b1 s1 and b2s1 sensors. And ultimately failure of state emission standards if the "smog machine" indicates "dilution".
The front differential is too weak for the constant torque applied to it from the AWD system no matter which engine (5.3 or 6.0) is installed in the vehicle.
The rear parking drum brakes are located behind the rear brake rotors. The parking brake assembly fails and the parking brake shoe rubs against the drum portion of the brake rotor damaging it. The fix requires new rotors and new hardware with an improved design to prevent the mounting assembly from failing again. A repair kit comes with instructions on how to modify the current backing plate to accept the new hardware.
The ABS/Traction Control/Stability Control systems are all inter-connected with each other and when something goes wrong with one system, it takes many hours to diagnosis, which transfers to lots of customer $$$ and then more $$$ for parts and labor repairs. It'* just an overly complicated system. I really hate when I am assigned a repair job involving these systems because it takes so much time (makes me feel as If my coworkers are looking at me like I was goofing off during my instructional courses). (incidentally, if anyone ever gets a stability with traction and abs system malfunction lights, you may want to check the wheel bearings. I don't know what it is, but when a wheel bearing gets worn/deteriorates, it messes with the associated electrical sensors.....I don't know why or how. My only guess is that a worn wheel bearing somehow changes the ohms resistance signal of the sensors wire harness or maybe the wheel bearing (friction) rolling resistance somehow creates a magnetic effect affecting the sensor. I don't know, this is something I've scratched my head about many times. Even my far more experienced supervisors with more ASE certifications can't explain this to me.
Other than those things I've mentioned, the Cadillac trucks are great vehicles. But some of those things I've mentioned are quite pricey. I would say from my experience dealing with this type of GM chassis the most reliable model would not be the Cadi, it would be a LIGHTER short wheel base Tahoe with the 5.3L engine. The Tahoe would be even more reliable with the manual 4x4 floor shifter which was available in GM trucks of this same year, but the manual shift 4x4 lever was never offered for Tahoe'*.