VERY loud clunk/jerk

Ok, I've got a 2000 Sierra on my hands. About 4 days ago, I noticed a popping sound when I pulled out of a parking spot, making a hard left. Ok, maybe its my u-joint I thought. After a day or so, and more pops to be heard, I noticed it was ONLY when I was accelerating while turning left from a complete stop. Hmmmm very strange to me. I jacked that baby up and checked to see if maybe there was anything loose or "out of place". Everything looked good to me, even the u-joints felt tight, and there was a good amount of play in the rearend.

After inspecting everything, I had to make a small road trip. Of course, the popping was there when turning left, and it seemed to be getting louder. Well, on my way back home, while accelerating from a red light, not only was there a popping sound, but also a very bad jerk. I've torn a rearend up in my Samurai before, so I know what it feels like. It felt kinda similar... So I try taking it easy on the way back, and to my amazement it popped and jerked taking off from a light, just going straight. Well, as I was turning right onto my street, out jumped that damn pop and jerk. Is my rearend trash? I don't feel anything while cruising or deccelerating, just during take off. I would greatly appreciate anyones help on this matter.

If it's not one thing, it's another! Damn the bad luck.

Well, I decided to go ahead an pull my diff cover off to see how bad it might be... The ring and pinion look fine (no nicks, scratches, missing teeth, etc.). But the spider gears were a different story. They are smashed, chipped, just plain nasty looking. The spider gears spin freely for a short time, then bind up. I'm guessing that was what the "jerking" was. So I guess now all I need is money to fix it. Ah, the joys of life. If anyone knows of a "cheap and/or easy" way to fix it, I'm all ears! Could I just weld the spider gears together and have posi, to fix the popping and jerking? I know that if the weld was to ever break, it could cause great damage to the ring and pinion though.