The pinion support wasn't what I was talking about, what I was talking about was this (see picture #1) it has a "cover" over the Yoke, while the other (see picture #2) doesn't have it. The center section that came with my Ranchero looked like picture #1 (it was an open diff), but the one I bought/got out of a F150 looked like picture #2 (this center section had a limited slip diff). So when I went to check it out and seal the center section, I swaped the pinion retainer over the center section with the limited slip and bolted into my Ranchero's rearend housing.
I should've said pinion retainer but for the life of me I couldn't remember what the Ford manual called it at the time.