I replaced this over the weekend on my 05 Duramax. P/N 19153614, $99.36 with Tax. Dealer said he charges $90 for the job.
I was expecting it to be a little easier based on most comments on here, but with the Duramax it is a little tougher to get to the lower bolt. In addition I had a hard time getting the new shaft into the lower shaft. Had to tap the top end from inside the cab with a hammer to get it in all the way so the bolt holes line up.
Less the time it took me to look for the nut for the lower bolt that I dropped, which disappeard somewhere under the truck, overall time was probably about 45 minutes.
So glad I finally got to this. It had been annoying me for about 8 months.
This is a very helpful thread.