I don't know whether the 1959
Overlanders utilized the same shower curtain arrangement as the 1964
, but if they did, finding an original type curtain will likely be nearly impossible. The original arrangement was a padded vinyl accordian door that was about 3.5 feet tall. The original door on my Overlander was falling apart when I purchased the coach in 1995 so I took what has been a fairly typical path . . . installed a track in the ceiling with dangling slides that had tabs to be sewn into the shower curtain . . . the curtain is a fabric shower curtain that was cut to conform to the curvature of the ceiling . . . and snaps attach it to the rearmost wall while velcro attaches it to the bulkhead wall where the shower abuts the wardrobe.
I wish that I could provide information about a reproduction, but I haven't heard of any. I certainly liked the original accordian door much better than the curtain.
Good luck with your projects!