I have a 98' Blazer and just had the transmission replaced recently. Not really sure if that has anything to do with it but the other day I went to take the truck for a drive when it started screeching loudly while I was driving down the road. All the electrical started dimming and it seemed like it was starting to stall. I was able to get it back home and figure out when it would start screeching. It seems to do it when I pull the shifter down between D and 3. I barely pull it out of D and down into 3 and it squeels like crazy. I've had conflicting ideas of what it could be.