It appears you can put the Transfer Case in Neutral, BUT this only if the engine can start and run. I did not indicate the Parking Brake was an issue with the Transfer Case, only when using the manual Park Override that is on the side of the transmission. Enabling the Parking Brake when using the shaft of the side of the transmission is to try to eliminate liability of someone gets rolled over by the vehicle while under the vehicle. So you should be able to flat tow the truck IF the truck starts and runs. If the engine does not start then it does not seem you can change the transfer case setting, either from in gear or out of neutral.
The issue with the parking brake is when the manual park override is used on the side of the transmission. While you can unplug the cables on the rear calipers, I believe there may be a few other options that I need to test and verify.
The issue with the parking brake is when the manual park override is used on the side of the transmission. While you can unplug the cables on the rear calipers, I believe there may be a few other options that I need to test and verify.