I'm not sure
Just posting what I found while ordering the rubber.
The one on the right was softer, and I think I ordered it from classic parts(chevy duty). I had ordered a second set from Tucker's in Las Vegas after glueing them on wrong.
The one on the left came in a box of parts I had.
Alan mentions the two types in his tech tip
http://www.alanhorvath.com/54chevy/doorubber.php
