Shock plate question

Both of these shock plates appear to be for 8 3/4. The plate on the right is more flat in the center. Anyone know why? Different parts supplier perhaps?

I believe on 1970 E-body the shock mounting stud is lower on the plate than 71-up
One on left appears to be 1970...flip them on their side and compare stud location

Here's a pic of the side and bottom. I added a third plate which isn't quite as worn as the original left plate.