Pretty good old trucks. I've had 2 '72 blazers in the past. The fiberglass rear glass frame is bad about cracking. Check the top for cracking also. Check the area where the steering box bolts to the frame for cracking around the bolt holes.
Both mine were CST models. Had the chrome gear levers and A/C.
Should be a cast iron transfer case with gears. make sure it shifts ok. Check the lockout front hubs to make sure they are free.