I'm almost certain someone did a cheap re-do on my bench at one time, but never changed the padding. Mine has batting (both bottom and back), with burlap and wires below that.
The bottom has an additional layer of super-heavy vinyl (which feels almost like a bathtub mat to the touch) below the burlap. Not the case on the back.
I figured I'd simply substitute foam in place of the batting for the back.