Well I searched through as many threads as I could find and I didnt find anything that matched my problem. I have only had my blazer a few weeks and I noticed when I bounced it around in the snow this loud grinding noise would act up under acceleration, mostly just from a stand still. I checked the tranny mounts and t-case mounts and those seem fine. I was thinking maybe U-Joints? It happens a lot when I am going over really bumpy stuff. It seems to happen more in 4hi than 2hi but it has happened in both with the hubs locked and unlocked. It sounds like it is coming from under my feet too. It kind of sounds like the tranny and t-case are bouncing around and hitting the crossmember, but I checked the mounts. ANy hellp?