What size is the O-ring on my power steering pressure hose??

Anyone know the size of o-ring that goes on the hose, The part that goes into the box. This is on a 74 A body but I imagine all 73 and up boxes are probably the same. (maybe even 71 and up)
It’s a Saginaw pump if that matter.

This is the o-ring included when you buy a new pressure hose like the one pictured

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