If your 4106 engine is stock, there should be a PTO near the torus fan drive that was used for the A/C compressor. Other '06 owners have used that PTO to mount both alternators and/or twin A6 GMC A/C compressors. A little tight, but you do have that access hatch between the rear wheel and the radiator that makes it a little easier.
FWIW & HTH. . .