Don Thompson

Hi, a newby here. I just bought a 1987 GL-10 Automatic 4X4 turbo (a mouthful) I like the car but it snowed this week and I found that even though the dash light is on for the 4x4 the rear wheels did not engage. It looks like the car has a new driveshaft. Where should I look first. I am fairly mechanical but this car is a new one on me. Thanks! Don