Alright so to get back to talking about the vibration. Long story short I got very tired of staring at it sitting sad in the garage. So I started to drive it, a few times a week to work. Put 300 miles on it or so.
The more I drove it and played with when it does it, how bad, what speed etc etc. I thought it is in the rear driveshaft. Like before everything pointed there, as the vibration is VERY fast and is much faster than wheel speed. Its also the first thing I changed when the vibration started.
To catch up. I bumped a rock (barely) put a few scratches and a VERY small dent in the tube near the pinion side of the drive shaft. It did not vibrate heading home from that wheeling trip. But it bugged me so I had it retubed to correct the small dent. It then vibrated and for more info can look back over the last few pages and catch up. I took it back and they retubed and balanced again. Still vibrated. I had a 2nd shop check balance and straight etc and still vibrated. I then purchased a 100% new drive line start to finish from Tom Woods Customs Drivelines. Still vibrated.
So at that point I though well crap Ive now been through 2 shafts and 3 shops etc. Can't all be incorrect so then rebuilt transfer case, still vibrated. Replaced tail shaft housing bushing, still vibrated. Torn down rear diff all looks good. Rebuilt locker. Still vibrated. Rebuilt rear diff. New pinion flange, gears and master install kit. Still vibrated. GRRRRRR.....
So back to driving it recently and everything still pointed at the driveshaft. So last Friday 4/15/16 I had my wife (she is such a great sport) run the Tom Woods driveshaft up to Tom Woods shop which is 1 1/2hrs North of us. I called and discussed everything. I'm sure they are like this guy is crazy. They then called Tuesday and said it was ready and they wanted to talk a bit more about the vibration. So I called and discussed it. From how I described everything they as well thought it is drive line or excess play somewhere. They then said they had triple checked the balance etc as we know we are trying to correct a driveshaft vibration. They said they made a small weight change. Said it is a good weight change on a normal driveshaft but this one with 1350 joints, 3" tube and double cardon upper joint it is a smaller change. He also described how these reverse slip yoke style with the double cardon joints are picky because there is naturally a small bit of play where it goes into the transfer case and since the mass is so high it is kinda of a problem child is how he described it. He had concerns that it also may be a bit short as to where the bushing is riding so to double check length. (same as on original receipt) He also asked me to check the plunge so fully stuff into transfer case and measure how far it is from rear flange. (1 3/4") Seal shows about 1/2" plunge where it rubs under driving which leaves roughly 1 1/4" it could be longer. So I will call them on that tomorrow. He wasn't sure if the change is large enough to correct the concern but to run it and see then we can discuss.
Well I picked it up on the way to Idaho on Tuesday for a funeral and installed it Thursday night. Drove it to work last Friday pulling a trailer even as I was headed to pick up extra metal a friend was getting rid of after work. First stretch from my house is 55 mph so all I could do before. I got it there and was smooth. I then went up to 60-62mph and is smooth.

What is this smooth things I am feeling!!!!!!! No idea what this smoothness is.

Very confused! So next stretch of road is also 55mph but is VERY fast usually on the way to work cops and all. Its is easily 65-75mph during rush hour as I live south of the main valley. 18 miles to work. So I got up to 65mph and was able to cruise.
So it was always there but was worst when in a no load condition and decreased 10% on coast load. And 40% or so when under driving forward load. So Was great I then went to my friends picked up the steel and headed home. Going home got up to 70mph and far as I could tell was 90% gone. Going to take rear tires in to be balanced Tuesday as they did have a little small hop from when I stripped all weights off looking for the issue.
So for now even if 70mph is the limit and it starts again it is now drive able! So a step in the right direction. It was the driveshaft all along. I have spent 1 1/2 years and $1,800 and lots of labor chasing this issue but was the original issue the whole time. So I am happy now its corrected but now slightly frustrated that between all the shops and times it was not corrected which caused me to look elsewhere. But that's all in the past and am happy that it is corrected.
Anyways its a long post but that's how I got to a corrected rig finally! Couldn't believe how great it felt to get it up to 70 again. That's part of what made the rig fun is I can wheel hard and then hit the freeway heading home. And that my wife can comfortably drive it on the freeway with our kids safely. Isn't that part of enjoying the rig is the fact that all my efforts in building a proper rig paid off? Not being scared to spend money in the correct places, taking my time and keeping it clean. The fact that I can let my wife drive it on the freeway and not be nervous about it is a great pride thing for me. May sound weird but its true so again VERY glad to have it back!!!!