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Close-up where the regenerative cooling tubes become bifurcated.

Also note that F-107-1 is displayed with no injector, offering a view of what appears to be the LOX dome. Compare this picture to an F-1 injector (e.g., the one in the F-1 at Stennis).

Vince Wheelock speculates that, as a test engine, this F-1 was torn down at some point in its life and when it was reassembled, the injector was not installed (and perhaps became a display piece on someone's wall).