******Update*****

So I pulled the front shaft tonight and indeed I do have a small amount of play in the center ball this will be replaced before it goes back in, Ive seen on here before that you can get these at advanced auto does anyone no the part# I am having trouble locating this.

After pulling the shaft We went for a drive and unfortunately the problem still persist I have inspected the roto flex and visibly yes it looks good I am having a hard time believing this could be the problem as the problem does not appear until after a period of driving.

I am leaning towards possibly differential or transfer case because it would seem to me that as whatever is heating up and expanding and combined with the fluid thinning after its hot that one of these could be the culprit so off to the parts store in the morning to pick up gear oil for the diffs I will inspect the fluid coming out for the possibility of contamination or a metallic finish. The last time this service was done around 160,000 I changed it with redline synthetic I am now at 205,000.

 

I really cant see a driveshaft being a problem, if the problem only occurs after 20 minutes of driving (unless the first 19 minutes of that drive are below 20MPH and the last 1 minute is over 50MPH).

Assuming you are talking about 20 minutes of the same driving (unlike 18 minutes to get to the highway) I am at a loss as to what to suggest. 45,000 on synthetic diff and T/C fluid is too soon for the fluid to be breaking down, unless you have done a lot of water crossings, and gotten water into the diffs and transfer case.

Going out on a limb here... what PSI are you running in your tires? Tire pressure will increase from the cold reading after the vehicle has been stationary for a long time. Is it possible that your tires may be balanced at the cold diameter, but become out of balance as the diameter of the tire increases as it heats up?

 

Tires are generally balanced at cold pressure.

 

Lol, I know this, but I was wondering if there was some irregularity in the tire that only shows itself once warm. I've seen stranger things.

 

*******Update******

Well after inspection of the diff fluid the rear looked almost perfect color a little on the black side but defiantly what I would consider normal.
The front on the other hand looked like a milkshake with metal flake not good at all so at this point I dont feel comfortable with just a fluid change so beginning tomorrow I will be pulling the cv's and pulling the diff to inspect I'm assuming at this point I am looking at ring and pinion new bearing and a T.T diff the only good news is that I will now get my T.T Diff I been wanting for some time now.

 

Nice. Sounds like you found it. Check the rear diff fluid as well. If someone sank it that deep in mud it's prob milk shake back there also. Flush it out too.

 

good to know you found your problem....hope everything works out for you