Here are 3 photos from my Adelaide HJ. The backing was covered by the previous owner in black vinyl, but thankfully nothing was touched on the panels.

You'll see the P/S and D/S chalk markings obviously to denote Passenger and Driver Side.
There ply has gone a little green with age, but there was a blue/green undercoat and then the off white.

Van seatback (1).jpg

Van seatback (2).jpg

Van seatback (3).jpg