I just took the yoke off the front of a GM AC Delco R-4 that I had sitting around. It was NOS for a 90's Chevy Suburban (I think....pretty sure).
Despite what I thought
(and what some have said on some of the other MB mailing lists and forums), there WAS an "X" and TWO oil journals on the inside; one to the front needle bearing and one to the shaft seal.
The journals point to the center (obviously), so mounting this R-4 with the "X" up would seem to be wise; gravity being what it is and all.
I have taken apart several other R-4's and never noticed this before. The yoke on this R-4 was the smaller version (there are two models of R-4's; lightweight and regular).