Re: How hard is it to rebuild a rag joint?
Not hard at all, but some will say you shouldn't do it and should replace the whole thing with a new GM coupler/rag joint that has the rivets like the original. If you get the repair kit with the new rubber disc, just make sure you keep the two metal shoulders from the original coupler and reuse them so that you have metal to metal contact when you bolt on the new rubber disc to the coupler.
I did mine last summer, cost about $10 at Napa for the kit which included a new rubber disc, bolts and pins. You'll need to remove the 12-pt bolt (don't remember the size off the top of my head) from the coupler and probably will have to move back the steering column and steering shaft to have enough room to pull the coupler/rag joint off the steering box. Then drill or grind off the rivets on the coupler and put it back together with the new stuff and back in.