Here is the sketch using the heights of 19 inches and 29-5/8 inches. If you move the back of the transfer case up it'll change that angle slightly, but shouldn't matter much for the proper angle at the other end.
The red angles are the flanges and the blue is the driveshaft to make it easier. The current angle between the diff flange and the driveshaft appears to be 7.7 degrees. This will go up if you raise the back of the transfer case.
Do the number look right on your end? The rounding is driving me nuts, but the driveshaft is really 7.7 degrees to the flange and 15.5 degrees to horizontal.
