Well I found out what it was. My rear diff was completely empty. For some time now I guess its been leaking around where the drive-shaft mates to the third member.
I couldn't figure out where all the oil came from under the back of the truck when I bought it (about 75 miles ago) and today while driving down the road, every turn I would make it would sound like I had a Detroit in the back.
I went to the store and got some Lucas 80/90 and filled it up after draining the little bit that was left in there. After taking it for a test drive I pulled over and looked under the truck and oil was dripping from that seal.
I dont know what the proper name of that seal is but I did read in my manual that I dont have to remove the third member to replace it, just drop the drive shaft.
One good thing was that it drives alot quieter now. I just hope I didn't destroy the rear since ive only driven it about 2 miles here and there back and forth to work.