Well, that's reassuring, though everything does NOT have to be aligned to the extent that I would think it would need to be with couplers. The u-joint interface would tolerate some left-right and / or up-down misalignment as long as the yoke bearing centerlines coincide at the u-joint trunnion centerline, where, as you say, the u-joint cups slip right into place. Mine do as well, but on my car, there is evidence that there has been at least one other drivetrain combination in the car at one time or another, because of visible mounting holes in the rearend upright that are not currently filled. I have no idea whether a line-up bar was used to set up my present combination.
Thank you very much for your input on this. I'll worry about it a lot less now, hearing you've run the same thing with no driveline failures.
John Williams