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A label taped to the injector handling fixture. It reads

Joint O-16, O-17, F-11

Injector

P/N: 209641

Partially cut off at the top of the photo is one of the injector's index holes.

The F-1 injector is indexed via two pins, one round and one diamond shaped, which fit into two index holes located 180° apart to ensure that the injector is installed in the proper orientation.

Both index holes are round, although they are different sizes. I believe that the diamond-shaped index pin has a larger diameter.

This index hole is noticeably larger than the other outer-dome attach bolt holes (and so I believe it is for the diamond-shaped index pin).