I have a 99 Blazer with Autotrac 4 x 4 (four buttons). In 2WD, I am able to only go a few yards and the Blazer starts making a growling, grinding sound and it is hard to steer or drive. I have checked and replaced the front differential fluid. I replaced the right half shaft (inner CV joint was leaking), upper and lower ball joints, replaced transmission fluid and filter. When I try to go into Auto4WD or 4WD, the light just blinks and then goes back to 2WD. What should I check next?

 

same tires all the way around?

 

Yes, same tires.