Mopar 10x2.5" brakes- anyone know the story on the two variants?

[benguin]

In a redo and restoration of my read 10" brakes, I've found there are two different styles- one with a round hole for the parking brake lever and another one with a trapezoid/rectangle hole in the web.   They defininitely cannot be interchangeable without machine work.  Parts listings from various manufacturers application catalogs are conflicting, with a very few listing both circle/rectangle and others just have one style.   Roseville's picture of the show show the rectangle version.

I'm currently working with the engineering team from Raybestos as their catalog shows circle, but I have received the rectangle version.   Anyone know what the story is on this?   Plant differences?  Parking brake mid-year changes?  Vendor confusion on year to year differences?

Pictures below showing the difference.  Appreciate your insightfulness in another Mopar mystery.

Thanks!
  Ben