thanks for your post - much appreciated. The date on the sweatband is 77 so yes mid-70's. The stamp in the liner is quite odd isn't it? Why would the US be the wrong way round? Very strange.
Anyway, just to pick your brains. Assuming this is a spring '45 shell, what make/model of liner would you think of fitting into it? How easy is it to replace the chinstraps with wartime one's?