I'm picturing sort of a U shaped yolk around the neck that attaches to the back armor and just gets tied to the shoulder armor or may even just float there. We know here is a metal bracket on the back armor where something attaches In regards to the air sack.
Also those clips on e shoulder look just like a square loop and a spring clip.
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For the clips it looks something like this http://www.strapworks.com/Swivel_Snap_p/ssss.htm
or maybe this https://www.strapworks.com/Metal_Beefy_Snaps_p/mbfs.htm
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And the loop is just this http://www.strapworks.com/Loops_p/ssl.htm
Also those clips on e shoulder look just like a square loop and a spring clip.
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For the clips it looks something like this http://www.strapworks.com/Swivel_Snap_p/ssss.htm
or maybe this https://www.strapworks.com/Metal_Beefy_Snaps_p/mbfs.htm
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And the loop is just this http://www.strapworks.com/Loops_p/ssl.htm