Bob.
On side kitchen vans of that era, the splash back is 3 sided like ours (see pic).
Although the one supplied had a punched out hinge mechanism then it shouldn't be too difficult to make one. The original ones hook into the back of the cooker to help them stay upright but a 3 sided one will stay up of its own accord. Also, you will be able to make a sit on top for it as we did, which can be used as an extra cooking shelf and extra splash guard.
Splash-Back.jpg - Bild entfernt (keine Rechte)
Randa