I hope that new driveshaft has a really-huge OD. If not, you're going to be in trouble at higher speed.
How, exactly, does a one-piece driveshaft work with a slip-yoke eliminator on the transfer case? Photos?
The driveshaft center bearing provides zero support for the transfer case. The two-piece driveshaft just eliminates the "whip" encountered with long driveshafts. Since there's a hinge in the middle of the two-piece shaft, the bearing merely connects the center of the shaft to something solid.