Driveshaft questions

[mechanixman]

My 52 1 ton had a 2 piece driveshaft. I just replaced the motor with a SBC and a t-5 transmission. I have just finished getting the motor running, and everything else to complete the the drivetrain. Right now I'm having some trouble with the driveshaft.

I was looking at it with the guy who was going to shorten the driveshaft for me when he noticed the center bearing can move back and forth quite a bit.. He was saying the bearing support shouldn't move that way, because it's the only thing keeping the drive shaft from moving. Now that it will have a slip yoke in the front, and the sliding driveshaft in the rear. I found a bushing on jim carter's but i didn't know if this would fix the problem or not so I went on the stovebolt forum and found some interesting things, but not what I was looking for. they mentioned that above certain speeds, you can get some serious driveshaft wobble.

So my questions are
I plan on driving my truck on the highway more often than not, should i even keep the 2 piece driveshaft?
I like to think that it's a little more protected, being that it'closer to the frame. I imagine the truck driving over brush, and through snow, and other obstacles that could come up and whack the drive shaft other components, and having 40% up high, and the back half come in at a steeper angles, it's less exposed to extra stress. (Basically more ground clearance) Please correct me if I'm wrong.

If I do keep it, what can I do to make sure the support and carrier bearing stay in place?
If I do keep it, What can I do to make sure it doesn't walk?

Thanks