I got the Service 4WD light on my '05 Tahoe Z71. No lights on the selector, couldn't change modes. Truck was driveable, so I believe it was in 2HI. Had the code read, C0327 which indicates the encoder sensor. I found instructions on this site for how to replace it. Everything came apart real easy, got the new sensor installed in the motor. Went to put the motor back on and the shaft had turned, the notch on the shaft no longer matches up with the gear on the motor. The notch on the gear is at around 11 o'clock position, the notch on the shaft is at 6'oclock. I read multiple comments (all apparently quoting the same bulletin) which says to use a crescent wrench to turn the shaft to the necessary position. How? I can turn it to about 9 o'clock, but no further. Plus, it immediately springs back to 6 o'clock. Someone suggested putting the truck in neutral (trans), jacking the rear tires off the ground, and turning the rear driveshaft while I try to turn the shaft. Did that, same results. Right now the truck is in the middle of my driveway, with the front end up on ramps and the rear on jack stands, with no front driveshaft. This is my daily driver, and I'm stranded without it. Does someone have any other suggestions?