Blazer is back on the road
So here was the problem... every time I hit the gas I didn't have any problems but when I let off the gas there was vibration and a grinding noise in the rear end. The auto shop said I needed to replace the whole rear diff, but after my buddy looked at it all it needed was to replace the Ujoints.
He said that the Ujoints had some slop in them and the vibrations caused the bolt for the pinion yoke to loosen up. So when I hit the gas the force would tighten up so there was no vibration/grinding noise, but when I let off the gas it would loosen up and grinding noise.
All fixed now =) and ready for the cruise. Let me know when we are going for that cruise!