I have a 98 S-10 blazer, 4x4 with a 4 speed automatic. Recently while driving it in 2 wheel drive it made a loud grinding noise and started vibrating really bad. It would not even move in 2 wheel drive. I put it in
4 wheel high to get it off the road, it was drivable but still making the noise, tried neutral to coast same problem. It would drive in reverse though without any problem. I removed the drive shaft ran it through the gears and it was quiet. Drove it on the front driveshaft in and out of the garage with no noise. At first I was leaning towards the transmission but now am thinking it might be something in the rear end. Any ideas or help would be appreciated.