Not always. I got a 9" center section that came from a Truck and it didn't have it. When I was put the 9" back together in my Ranchero, I took the pinion plate onto the truck one becaue it was a limited slip unit.
Say what???? First off all Ford 9" have the pinion support. If they didn't there would be no way to adjust the pinion depth cause it's done with shims behind the pinion support plate. And what's up with that English? Sure not easy to make out what your saying!