I think you have a NVG 246 transfer case, if so try this - This transfer case also has a Neutral position. A shift to the Neutral position allows the vehicle to be towed without the rear axle rotating the transfer case main shaft and the transmission output shaft. Neutral position may be obtained only if the following criteria has been met:
The key is ON. The automatic transmission is in Neutral, clutch depressed on manual transmissions. The vehicle speed is below 5 km/h (3 mph). The transfer case is in 2HI mode. Once these conditions have been met, press and hold both the 2HI and
4LO buttons for 10 seconds. When the system completes the shift to neutral, the red neutral lamp will illuminate.