'99 Sierra 1500 4wd Z71 u-joint problem?

In the last month, my truck (118k Miles) has developed the typical "U-joint going out squeak". I took it in and had the local tranny/differential shop take a look at it. Expected for them to say "yup, u-joint is bad", and pay them to replace it. After their "Free estimate", they came to the conclusion that they aren't sure what it is for sure. Mentioned that GM has had problems with the yokes, and they are "like gold" and very expensive to replace....however, if I wanted to spend the $500 to replace the yoke and the u-joints, they would be happy to schedule an appt. for me.....here's the kicker....they said, "This may or may not take care of the problem....and that GM usually just tells the customer to live with it instead of fixing it?" Excuse me? If I wanted a squeaky piece of crap, I would have bought a Ford. Has anyone heard of this? Obviously, I told them not to touch it, and brought it home. Talked to another mechanic that can change the u-joint out for about an hour of shop time. I'm not gonna attempt it myself as I don't have a big enough bench vice....That Yoke B/S is bothering me though. I had never heard of it before. If anyone can shed any light on this for me, please do. The Tranny shop has been very fair with me in the past and i've given them all my business up until this. Thanks! (BTW--i'm referring to the squeak in the back. So, Rear drive shaft, not front, not sure if this matters or not.)

if the u-joint is for sure bad then change it. but if you want change them both and if the squeek goes away that was the problem, as for the yolk i have never heard of any problem with them. sometimes ive heard a mechanic i work with say they go bad every now and then but not often. as for the guy at the shop i would go to the manager and tell him what the guy said becuase i know for a fact a large corporation like that wouldnt tell you to do something like that.

Thanks slredstorm62, that is kinda what I thought too. There is no way that GM is gonna tell you to live with it, they are gonna want to try to fix it, whether they do or not. The unfortunate part about the guy at the shop is that he IS the manager. I don't plan on taking anything back to him. I'll repost if the u-joints dont' help.