2wd squeeling and vibrating while driving...

Good day, all! So, yes this is my first ever post here. I have been hanging in these forums for a long time, and ya'll have always helped me fix my issues without ever posting anything. Well, today's the day.
Ok, so I've read a lot of posts on 4wd transfer case/transmission yoke slippage and such. I have a 2wd, with the 2.3L, and was told the other day that the cause of my vibration is 'output shaft is slipping'. I've been hunting for info ever since.
My question is... is the output shaft the same as the transmission yoke (there are evidently different names for some of this stuff), and if not, is the output shaft what the transmission yoke slides onto? Or am I way off?
Since I have 2wd, I have a one piece driveshaft, so there isn't a slip yoke, per se, to grease that would stop the thunking/clunking on a 4wd.
Next question, if this transmission yoke (or whatever it's called today) IS slipping, can I change that myself by disconnecting the driveshaft at the differential and sliding it out of the transmission. I've been quoted huge labor prices by the guy that said it was slipping to begin with.
I have yet to get a price on the part itself, because I have yet to find it. I have looked, and am a little baffled about which type of tranny I have, and can't seem to narrow down the part.
Yes, there is another glitch. Yes, I did put a 5" lift kit on last June. I can't be surprised to be havine problems, however I am surprised to have gone so long without having any from it. If I find this part and replace it, I would like to replace the u-joints, too. I should probably get something that is a little more forgiving than the OEM ones that I have. I really cranked up that driveshaft angle, and that's probably at the root of this whole thing.
Any help, advice, or whatever would be great. I'm feeling a little lost here.

Ok, here's the new news. I went to a driveshaft shop yesterday, and the guy was really helpful. He crawled up under my truck and everything, and pretty much told me what I needed to do.
He said not to worry about the tranny yoke, and recommended that I change the u-joints. He commented that the driveshaft angle wasn't "that bad", yet suggested that I get form pinion shims to raise the angle of the rear axle. 2 degrees max.
Here's the kicker. I go to the parts store to get the u-joints today, and come home, and take the driveshaft out. That was easy. I got the old u-joints out. That was easy, too. I went to put the new u-joints in, and turns out that of the 4 bearings (one on eash arm of the cross), 2 are one size, and 2 are slightly larger. They are in pairs, the top and bottom, and the left and right.
I'm a little baffled now, and those two that are slightly larger won't go in at all. I'm afraid to beat on it, and take a chance breaking the hole. It's that same thing on both ends of the driveshaft. All eoght holes are the smaller size.
Do I buy another set of u-joints, and mix and match? I know this isn't the first time that someone has run across this. I'm a little hacked, since I had to take the whole things apart to find this out.
Here's the upside. In the process of dismantling the u-joints, I definately has one that was bad. There is a single bearing on one of the joints that is shot- there aren't any needle bearings in it at all. Evidently this was the problem all along.
So, if I buy another set, can I mix and match the parts so that I have two that's work? They will all fit then. Has anyone else ever had this issue?