Sorry this is all still new to me, my stock driveshaft still has the splined yoke attached on the front, not sure about the other end. So you are saying when I take mine to get shortened they would cut off one end end weld back in the same orientation and that's it? Once that's done it doesn't matter what orientation the driveshaft is reinstalled?
The slip yoke has a blank master spline cut but the tail shaft does not. The shafts are balanced off the car so just stick it in any old way. Two piece shafts like in trucks with a slip joint must be indexed properly if taken apart though.