Personally, I doubt you had a problem with your old transfer case or your transmission. You need to understand that your truck has 3 differentials, one in each axle and one in the transfer case. In addition, you have a viscuous coupler, which might be "a round hub thats splined in the center and splined on the outside " but I'm not sure, as you are difficult to understand. You also have an electric locker in the transfer case differential, which automatically engages when the transfer case is shifted into low range. That's key here, as it indicates that your problem is occuring after the t-case differential, although there is a minute possibility that the problem is in the differential itself. I've never seen or heard of that, and you've already swapped out the t-case, so I think you can rule that out.
From what I can understand from your posts, it sounds as if there is something broken in one of your axles- could be a differential, could be an axle shaft, could be a birfield, could be a front hub drive flange. The drive flange is the more common point of failure. In high range, power from the transmission is distributed through the t-case diff and viscuous coupler. The viscuous coupler attempts to ensure that you have some power going to both front and rear axles, but will allow slippage. It will slip less as it heats up. This probably explains why your truck moves at all in high range. If something in one of your axles is broken, all the power from the t-case will be lost at that point. The parking pall will not stop the truck because the broken part is allowing the drive train to spin independant of the transmission. In low range, the t-case differential locker forces equal power to both axles, which explains why your truck shifts normally, and more importantly why the parking pall stops the truck. I don't have the capacity to explain this better, but this forum has many threads which further describe what's going on, as well as some that detail how to determine if your front drive flanges are stripped. I would highly recommend you browse through the FAQ section at the top of the thread list, as well as use the search function. If you don't understand how your truck's drive train works, you are at a severe disadvantage trying to diagnose problems. Again, I seriously doubt you had a problem with your transmission or t-case in the first place, but it sounds as if you've spent a lot of time and money trying to 'fix' them.
It's also entirely possible that I have no idea what's wrong with your truck because I don't understand what you're describing. If you want more help from the folks here, I would suggest you learn how to use capitalization and punctuation to make your posts readable. I'm getting a headache trying to understand what you are writing, and I'm one of the more patient people here. You will get a lot more help from the many knowledgeable members if they can understand what you are saying without having to work at it. It's hard enough to diagnose a problem over the internet without having to decipher the meaning of the posts. Perhaps you could have a friend try to describe what the problem is if you are unable.
You might also give us some history- how long you've had the truck, did you buy it in this condition or did it get this way while you were driving it, your location, any modifications, repairs, maintenance, etc.
-Spike
